Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS4944298 A
Publication typeGrant
Application numberUS 07/355,588
Publication dateJul 31, 1990
Filing dateMay 23, 1989
Priority dateMay 23, 1989
Fee statusPaid
Also published asDE69031823D1, DE69031823T2, EP0426828A1, EP0426828A4, EP0426828B1, WO1990014126A1
Publication number07355588, 355588, US 4944298 A, US 4944298A, US-A-4944298, US4944298 A, US4944298A
InventorsJason A. Sholder
Original AssigneeSiemens-Pacesetter, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Atrial rate based programmable pacemaker with automatic mode switching means
US 4944298 A
Abstract
An atrial rate based programmable pacemaker including means for preventing the heart from being paced at an upper rate limit for prolonged periods of time is disclosed which paces the heart at a rate that follows or tracks the atrial rate up to the upper rate limit of the pacemaker, at which point the pacemaker stimulates the heart at the upper rate limit, but also continues to monitor the atrial rate. If the monitored atrial rate exceeds a second upper rate limit, a fast atrial arrhythmia or tachycardia condition is deemed to exist, and the pacemaker automatically switches from its existing mode of operation to an alternate mode of operation in an attempt to break or terminate the fast atrial condition. Alternate embodiments include using an external activity or physiological sensor to control the pacing rate in the new pacing mode, and the inclusion of means for periodically verifying that atrial sensing is occurring, and means for automatically adjusting the sensitivity of the atrial channel as required.
Images(5)
Previous page
Next page
Claims(20)
What is claimed is:
1. An improved dual chamber pacemaker having programmable modes of operation, said pacemaker being capable of stimulating the atrial and the ventricular chambers of the heart, said pacemaker including programming means for selectively allowing the pacemaker to be programmed to operate in an atrial rate based mode of operation, and atrial sensing means for sensing atrial activity occurring in the atrial chamber, including atrial rate of said atrial activity, wherein the improvement comprises:
first sensing means for monitoring said atrial rate and sensing whether said atrial rate exceeds a first prescribed threshold;
means for providing a stimulating pulse to a selected chamber of the heart at a maximum upper rate in the event said atrial rate sensed by said first sensing means exceeds said first prescribed threshold;
second sensing means for monitoring said atrial rate above said first prescribed threshold and sensing whether said atrial rate exceeds a second prescribed threshold, said second threshold being at a higher rate than said first threshold; and
means for automatically switching the mode of operation of said pacemaker from said atrial rate based mode of operation to a selected alternate mode of operation in the event said atrial rate exceeds said second prescribed threshold.
2. The programmable pacemaker of claim 1 further comprising:
third sensing means for monitoring said atrial rate during said alternate mode of operation and sensing whether it drops below a third prescribed threshold; and
means for automatically switching the mode of operation of said pacemaker from said alternate mode of operation back to said atrial rate based mode of operation in the event said atrial rate falls below said third prescribed threshold.
3. The programmable pacemaker of claim 2 wherein said first, second and third prescribed thresholds are programmably selectable through said programming means.
4. The programmable pacemaker of claim 2 wherein said first prescribed threshold comprises a rate which is at least equal to said maximum upper rate at which stimulating pulses are provided to the selected chamber of the heart.
5. The programmable pacemaker of claim 4 wherein said first prescribed threshold comprises a rate which is at least 150 beats per minute and said second prescribed threshold comprises a rate which is at least 200 beats per minute.
6. The programmable pacemaker of claim 1 further comprising:
a physiological sensor coupled to said pacemaker, wherein said automatic switching means is capable of coupling said physiological sensor to said stimulating pulse providing means during said alternate mode of operation, and for modifying the operation of said pulse providing means to provide stimulating pulses to a selected chamber of the heart at a rate controlled by said physiological sensor during said alternate mode of operation.
7. The pacemaker of claim 1 further comprising:
atrial sensitivity adjustment means for automatically checking the sensitivity of said atrial sensing means at selected intervals to determine its ability to sense P-waves, and for automatically adjusting said atrial sensing means to sense P-waves in the event that P-waves are not being sensed.
8. The pacemaker of claim 7 wherein said atrial sensitivity adjustment means comprises:
means for switching said pacemaker to a test mode of operation;
means for monitoring said atrial sensing means during said test mode for a prescribed period of time to determine if any P-waves are detected; and
means for adjusting said atrial sensing means so that lower amplitude P-waves can be detected by said atrial sensing means in the event no P-waves are detected by said monitoring means during said prescribed period of time.
9. The pacemaker of claim 8 wherein said means for adjusting said atrial sensing means comprises:
means for adjusting the sensitivity of said atrial sensing means in a series of incremental adjustments until said P-waves are detected.
10. The pacemaker of claim 9 wherein said pacemaker further comprises:
means for switching the pacemaker mode of operation from said test mode to a prescribed alternate mode of operation in the event P-waves are not detected after the sensitivity of said atrial sensing means has been adjusted through all of said fixed incremental adjustments, whereby said alternate mode of operation provides an indicia that said atrial sensing means was unable to detect P-waves.
11. A dual chamber pacemaker having first and second channels, said first and second channels including sensing means for sensing cardiac activity and pulse generating means for providing pacing pulses in the absence of cardiac activity in the atrial and the ventricular chambers of the heart, respectively, said pacemaker comprising:
control means for controlling said sensing means and said pulse generating means of said first and second channels in a prescribed mode of operation, said control means comprising:
means for detecting a rate of cardiac activity as sensed by said sensing means in said first channel; and
means for triggering said pulse generating means to provide pacing pulses in said second channel at a rate which is the lesser of said rate of cardiac activity detected in said first channel or a maximum tracking rate; and
means for automatically changing said prescribed mode of operation in the event said rate of cardiac activity detected in said first channel exceeds a specified threshold level, said specified threshold level comprising a rate which is greater than said maximum tracking rate.
12. The pacemaker of claim 11 further comprising:
means for automatically changing the mode of operation of said pacemaker back to said prescribed mode of operation in the event said rate of cardiac activity detected in said first channel drops below a second specified threshold level, said second specified threshold level comprising a rate that is less than said maximum tracking rate.
13. The pacemaker of claim 11 further comprising:
means for automatically adjusting the ability of said first channel to sense cardiac activity.
14. The pacemaker of claim 11 further comprising:
a physiological sensor for sensing physiological events indicative of a need to change the rate of said pulse generating means, and wherein said means for automatically changing the prescribed mode of operation comprises means for coupling said physiological sensor to said pulse generating means and for controlling said pulse generating means to provide pulses in said second channel at a rate determined by the physiological events sensed by said physiological sensor.
15. A method of operating a dual chamber programmable pacemaker, said pacemaker being capable of operating in a variety of modes of operation and being initially programmed to operate in an atrial rate based mode of operation, said pacemaker comprising means for sensing cardiac activity in the atrial and the ventricular chambers of a heart, and means for selectively providing a stimulating pulse to either chamber of the heart at prescribed times and under prescribed conditions, the method comprising the steps of:
(a) sensing when the atrial rate exceeds a first rate threshold;
(b) providing a stimulating pulse to a selected chamber of the heart at a maximum upper rate in the event the atrial rate sensed in step (a) exceeds said first rate threshold;
(c) monitoring the atrial rate above said first rate threshold up to a second rate threshold; and
(d) automatically switching the mode of operation of said pacemaker from said atrial rate based mode of operation to a selected alternate mode of operation in the event the atrial rate exceeds said second rate threshold.
16. The method of claim 15 further comprising the steps of:
(e) monitoring the atrial rate during said alternate mode of operation; and
(f) automatically switching the mode of operation of said pacemaker from said alternate mode of operation back to said atrial rate based mode of operation in the event the atrial rate falls below a third rate threshold.
17. The method of claim 15 further comprising the step of:
(e) controlling the rate at which stimulating pulses are provided by said pacemaker during said alternate mode of operation in accordance with a rate signal provided by a physiological sensor coupled to said pacemaker.
18. The method of claim 15 further comprising the step of:
(e) checking the sensitivity of the atrial sensing means at selected intervals to determine its ability to sense P-waves; and
(f) automatically adjusting the sensitivity of the atrial sensing means to sense P-waves in the event that P-waves are not being sensed.
19. The method of claim 18 wherein the step of checking the sensitivity of the atrial sensing means comprises:
monitoring the atrial sensing means for a prescribed period of time to determine if any P-waves are detected.
20. The method of claim 18 wherein the step of adjusting the sensitivity to sense P-waves comprises:
changing the sensitivity of the atrial sensing means by a first discrete increment;
checking the sensitivity of the atrial sensing means to determine if P-waves are sensed;
if P-waves are not sensed, changing the sensitivity of the atrial sensing means again by a second discrete increment, checking the sensitivity of the atrial sensing means again to determine if P-waves are sensed, and so on, through a series of discrete increments, until P-waves are sensed.
Description
BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to programmable implantable pacemakers, and more particularly to an implantable dual chamber pacemaker programmed to operate in an atrial rate based mode, wherein mode switching means are provided for automatically switching the mode of operation of the pacemaker from one mode to another in the event the sensed atrial rate exceeds a prescribed upper rate limit.

Modern programmable pacemakers are generally of two types: (1) single chamber pacemakers, and (2) dual chamber pacemakers In a single chamber pacemaker, the pacemaker provides stimulation pulses to, and/or senses cardiac activity within, a single chamber of the heart, e.g., either the right ventricle or the right atrium. In a dual chamber pacemaker, the pacemaker provides stimulation pulses to, and/or senses cardiac activity within, two chambers of the heart, e.g., both the right ventricle and the right atrium. Typically, only the right atrium and/or the right ventricle is coupled to the pacemaker because of the relative ease with which a pacing lead can be transvenously inserted into either of these chambers. However, the left atrium and left ventricle can also be paced just as effectively providing that suitable electrical contact is made therewith.

In general, both single and dual chamber pacemakers are classified by type according to a three letter code. In this code, the first letter identifies the chamber of the heart that is paced (i.e., that chamber where a stimulation pulse is delivered), with a "V" indicating the ventricle, an "A" indicating the atrium, and a "D" indicating both the atrium and ventricle. The second letter of the code identifies the chamber wherein cardiac activity is sensed, using the same letters to identify the atrium or ventricle or both, and wherein a "0" indicates no sensing takes place.

The third letter of the code identifies the action or response that is taken by the pacemaker. In general, three types of action or responses are recognized: (1) an Inhibiting ("I") response wherein a stimulation pulse is delivered to the designated chamber after a set period of time unless cardiac activity is sensed during that time, in which case the stimulation pulse is inhibited; (2) a Trigger ("T") response wherein a stimulation pulse is delivered to a prescribed chamber of the heart a prescribed period after a sensed event; (3) or a Dual ("D") response wherein both the Inhibiting mode and Trigger mode are evoked, inhibiting in one chamber of the heart and triggering in the other.

Thus, for example, a DVI pacemaker is a pacer (note that throughout this application, the terms "pacemaker" and "pacer" may be used interchangeably) that paces in both chambers of the heart, but only senses in the ventricle, and that operates by inhibiting stimulation pulses when prior ventricular activity is sensed. Because it paces in two chambers, it is considered as a dual chamber pacemaker. A VVI pacer, on the other hand, is a pacer that paces only in the ventricle and senses only in the ventricle. Because only one chamber is involved, it is classified as a single chamber pacemaker. It should be noted that most dual chamber pacemakers can be programmed to operate in a single chamber mode.

Much has been written and described in the art about the various types of pacemakers and the advantages and disadvantages of each. For example, reference is made to U.S. Pat. No. 4,712,555, to Thornander et al., co-invented by the present applicant, wherein some helpful background information about pacemakers and the manner in which they interface with a patient's heart is presented. This patent is hereby incorporated herein by reference.

One of the most versatile programmable pacemakers available today is the DDD pacemaker. This pacer represents a fully automatic pacemaker which is capable of sensing and pacing in both the atrium and ventricle. When functioning properly, the DDD pacer represents the dual chamber pacemaker with the least number of drawbacks. It is typically implanted in patients in an effort to maintain AV synchrony while providing bradycardia support.

In general, DDD pacing has four functional states: (1) P-wave sensing, ventricular pacing (PV); (2) atrial pacing, ventricular pacing (AV); (3) P-wave sensing, R-wave sensing (PR); and (4) atrial pacing, R-wave sensing (AR). Advantageously, for the patient with complete or partial heart block, the PV state of the DDD pacer tracks the atrial rate, which rate is set by the heart's S-A node, and then paces in the ventricle at a rate that follows this atrial rate. Because the rate set by the S-A node represents the rate at which the heart should beat in order to meet the physiologic demands of the body, at least for a heart having a properly functioning S-A node, the rate maintained in the ventricle by such a pacemaker is truly physiologic.

Those skilled in the art have long recognized the advantages of using an atrial rate based pacemaker. For example, U.S. Pat. No. 4,624,260, to Baker, Jr., et al., discloses a microprocessor-controlled dual chamber pacemaker having conditional atrial tracking capability. Similarly, U.S. Pat. No. 4,485,818, to Leckrone et al., discloses a microprocessor-based pacer which may be programmed to operate in one of a plurality of possible operating modes, including an atrial rate tracking mode.

Unfortunately, in some instances, it is possible for a given patient to develop fast atrial rhythms which result from pathological tachycardias and fibrillation. In these cases, the DDD pacer will pace the ventricle in response to the sensed atrial disrhythmia up to the programmed maximum tracking rate. While this upper rate limit is designed into the pacemaker to protect the patient from being paced too fast, it is not desirable to pace at the maximum upper rate limit for a long period of time, else the heart cannot efficiently perform its function of pumping blood through the body.

Therefore, attempts have been made in the art to prevent such atrial arrhythmias from developing. For example, U.S. Pat. No. 4,722,341, to Hedberg et al., teaches an atrium-controlled pacemaker wherein the pacemaker temporarily switches from an atrial rate based mode to a non-atrial rate based mode for a fixed number of stimulation pulses if the sensed atrial activity indicates an atrial arrhythmia may be developing. Unfortunately, however, for some patients, a temporary switching from one mode to another may not be sufficient to correct or arrest the arrhythmia.

What is needed is an atrial rate based pacemaker which will not only sense the atrial arrhythmia once it develops, but which will also take whatever corrective action is needed, for however long (i.e., not just temporarily), to prevent the heart from being paced at the maximum upper limit for long periods of time.

It is known that the dual chamber pacemaker itself may undesirably support (and even induce) some cardiac arrhythmias. This process is described, for example, in U.S. Pat. No. 4,788,980, to Buchanan et al., where such arrhythmias are referred to as a pacer mediated tachycardia, or PMT. The referenced patent discloses a particular technique for recognizing a PMT and terminating it once it develops. Similarly, U.S. Pat. No. 4,712,556, to Baker, proposes another technique for identifying PMT's, and proposes yet another technique for terminating such PMT. Still another patent, U.S. Pat. No. 4,554,921, to Boute et al., teaches modifying the atrial refractory period of the pacemaker in an attempt to break or terminate a PMT.

Regardless of the source of the arrhythmia, however, whether caused by a PMT or by other factors, if left unchecked, the DDD pacer will track the fast atrial rate and pace the ventricles up to the maximum tracking rate for a long period of time, resulting in low cardiac output. What is needed, therefore, is a method or technique for preventing an atrial rate based pacemaker from pacing the heart at the maximum pacing rate for prolonged periods of time, even when an atrial arrhythmia is present.

Sometimes it is possible at the time of implant of a pacemaker to determine whether an atrial fibrillation, atrial flutter, or atrial tachycardia condition is going to develop. In such instances, the pacemaker may always be programmed to operate in a different mode of operation, the leads may be repositioned within the heart, or other actions may be taken to minimize the likelihood of such arrhythmias occurring. Unfortunately, however, it is not always possible at the time of implant to determine whether a patient will develop an arrhythmia as a result of pacing.

Therefore, if such arrhythmias subsequently occur, they must be treated using other techniques, such as through the administration of drugs. Needless to say, the administration of drugs requires the attendance of a physician. Unfortunately, however, a physician is not always present when such arrhythmias develop, and even when a physician is available, such drugs undesirably also suppress the ability of the S-A node to increase the sinus rate during periods of exercise, emotional stress, or other physiologic stress. Thus, the use of such drugs effectively prevents the pacer from functioning as a true physiologic rate-responsive pacer.

What is needed is an approach for dealing with arrhythmias which develop after implant without necessitating the attendance of a physician and without compromising the pacer's ability to function as a physiologic rate-responsive pacer.

It is also possible that the atrial arrhythmia may be caused by the pacemaker's inability to sense P-waves. In such an instance, the paced competition with the native atrial activity may precipitate an atrial tachycardia or fibrillation. This inability to sense P-waves may be caused by numerous factors, but is usually caused by electrode dislodgement or movement, tissue growth, or other events which may occur several days or weeks after implant.

The ability of the pacemaker to sense P-waves is referred to as atrial sensitivity. At implant, the atrial sensitivity is adjusted based on various tests in order to ensure that P-waves are sensed with an adequate margin of safety. However, even this margin of safety may disappear over time, and it thus becomes necessary for a physician to reprogram the atrial sensitivity so that P-waves will be sensed. However, until reprogramming of the atrial sensitivity takes place, there is some possibility that P-waves will not be sensed, resulting in the undesirable atrial arrhythmias described above.

Thus, what is needed is a pacemaker which includes means for periodically checking, and adjusting as required, the atrial sensitivity, thereby assuring that P-waves will always be sensed by the pacemaker. U.S. Pat. No. 4,708,144, to Hamilton et al., represents one approach known in the art for automatically controlling the sensitivity of the pacemaker.

Further, with an atrial rate based dual chamber pacemaker, there is always the problem that a sustained activity period of the patient, resulting in a naturally high sinus rate, may be interpreted by the pacemaker as a pathological atrial arrhythmia. Hence, an atrial rate based pacemaker needs to incorporate some means to readily distinguish a sustained pathological atrial arrhythmia from a sustained activity period, and take appropriate action in each instance.

Advantageously, the pacemaker described herein, including the method of operating such pacemaker, addresses the above and other needs.

SUMMARY OF THE INVENTION

The disadvantages and limitations of the background art discussed above are overcome by the present invention. With this invention, an atrial rate based programmable pacemaker is provided which advantageously includes means for preventing the heart from being paced at the upper rate limit of the pacemaker for prolonged periods of time in the event the atrial rate exceeds a prescribed upper rate limit. The pacemaker includes means for operating in a prescribed dual chamber mode of operation, such as DDD, wherein the heart is paced at a rate that follows or tracks the atrial rate up to the upper rate limit of the pacemaker. When the atrial rate exceeds the upper rate limit, the pacemaker stimulates the heart at the upper rate limit, but also continues to monitor the atrial rate.

If the monitored atrial rate exceeds a second upper rate limit, e.g., a tachycardia rate limit, a pathological atrial arrhythmia or tachycardia condition is deemed to exist, and the pacemaker automatically switches from its existing mode of operation to an alternate mode of operation, e.g., a single chamber mode of operation. This mode switching is performed for the purpose of breaking or terminating the fast atrial condition. While in the alternate mode of operation, the atrial and/or ventricular rate continues to be monitored, and as soon as the rate drops to an acceptable level, the pacemaker automatically switches back to its initial atrial rate based mode.

In one embodiment of the invention, an external physiological sensor may optionally be utilized in the pacemaker to control the pacing rate of the pacemaker in the alternate pacing mode. This action ensures that the pacemaker is attempting to pace the heart at an appropriate heart rate based on the patient's actual physiologic needs at a time when the heart may be beating at an excessive rate, e.g., during a tachycardia or other arrhythmia. As with the first embodiment, as soon as the atrial or ventricular rate drops to an acceptable level, the pacemaker automatically switches back to its initial mode of operation.

In a still further embodiment, the pacemaker includes means for periodically verifying that atrial sensing is occurring. If a determination is made that atrial sensing is not occurring, an adjustment mode is initiated during which the sensitivity of the atrial channel is automatically adjusted, as required.

It is thus a feature of the present invention to provide a programmable pacemaker which prevents the heart from being paced at the maximum rate of the pacemaker for prolonged periods of time. It is a further feature of the invention to provide such a pacemaker wherein the pacemaker continues to sense the rate of cardiac activity even when that rate exceeds the upper rate limit of the pacemaker.

Yet another feature of the invention is to provide such a pacemaker wherein the mode of operation of the pacer automatically switches from a first mode to a second mode in the event the sensed cardiac activity exceeds a prescribed second upper limit, this second upper limit being above the pacemaker's normal upper rate limit. While in this second mode of operation, an additional feature of the invention provides for the continued sensing of the prescribed cardiac activity and the automatic switching of the pacemaker back to its first mode of operation as soon as the prescribed cardiac activity returns to a normal level.

Still another feature of the invention provides such an automatic mode switching pacemaker wherein the pacing rate of the pacemaker while in its second mode of operation is controlled by an external physiological sensor, such as an activity sensor. A still further feature of the invention provides a programmable pacemaker wherein the sensitivity of the sense amplifier(s) used to sense cardiac activity may be automatically adjusted at prescribed times or intervals. Finally, all of the aforesaid advantages and objectives are achieved without incurring any substantial relative disadvantage.

DESCRIPTION OF THE DRAWINGS

These and other advantages of the present invention are best understood with reference to the drawings, in which:

FIG. 1 is a block diagram of a dual chamber programmable pacemaker;

FIG. 2 is a block diagram of one possible embodiment of the control logic of the pacemaker of FIG. 1;

FIG. 3 is a simplified state diagram of the pacemaker of FIG. 1 when operating in accordance with one embodiment of the present invention; and

FIGS. 4A and 4B are flow chart diagrams illustrating the operation of the pacemaker of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is of the best presently contemplated mode of practicing the invention. This description is not to be taken in a limiting sense but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be ascertained with reference to the appended claims.

Before describing the invention in more detail, a brief review of cardiac physiology may be helpful. Essentially, the heart is a pump which pumps blood throughout the body. It consists of four chambers, two atria and two ventricles. In order to efficiently perform its function as a pump, the atrial muscles and ventricular muscles must contract in a proper sequence and timed relationship.

In a given cardiac cycle (corresponding to one "beat" of the heart), the two atria contract, forcing the blood therein into the ventricles. A short time later, the two ventricles contract, forcing the blood therein to the lungs (right ventricle) or through the body (left ventricle). Meanwhile, blood from the body fills up the right atrium and blood from the lungs fills up the left atrium, waiting for the next cycle to begin. A typical healthy adult heart may beat at a rate of 60-70 beats per minute (bpm) while at rest, and may increase its rate to 140-180 bpm when the adult is engaging in strenuous physical exercise, or undergoing other physiologic stress.

The healthy heart controls its own rhythm naturally from its S-A node, located in the upper portions of the right atrium. The S-A node generates an electrical impulse at a rate commonly referred to as the "sinus" rate. This impulse is delivered to the atrial tissue when the atria are to contract; and, after a suitable delay (on the order of 40-80 milliseconds), is delivered to the ventricular tissue when the ventricles are to contract.

When the atria contract, a detectable electrical signal referred to as a P-wave is generated. When the ventricles contract, a detectable electrical signal referred to as an R-wave is generated. The R-wave is much larger than the P-wave, principally because the ventricular muscle tissue is much more massive than is the atrial muscle tissue. The atrial muscle tissue need only produce a contraction sufficient to move the blood a very short distance, from the respective atrium to its corresponding ventricle. The ventricular muscle tissue, on the other hand, must produce a contraction sufficient to push the blood over a long distance, e.g., through the complete circulatory system of the entire body.

Other electrical signals or waves are also detectable within a cardiac cycle, such as a Q-wave (which immediately precedes an R-wave), an S-wave (which immediately follows an R-wave), and a T-wave (which represents the repolarization of the ventricular muscle tissue).

It is the function of a pacemaker to provide electrical stimulation pulses to the appropriate chamber(s) of the heart (atria or ventricles) in the event the heart is unable to beat on its own, i.e., in the event either the S-A node fails to generate its own natural stimulation pulses at an appropriate sinus rate, or in the event such natural stimulation pulses are not delivered to the appropriate cardiac tissue. Most modern pacemakers accomplish this function by operating in a "demand" mode wherein stimulation pulses from the pacemaker are provided to the heart only when it is not beating on its own, as sensed by monitoring the appropriate chamber of the heart for the occurrence of a P-wave or an R-wave. If a P-wave or an R-wave is not sensed within a prescribed period of time (which period of time is most often referred to as the "escape interval"), then a stimulation pulse is generated at the conclusion of this prescribed period of time and delivered to the appropriate heart chamber via a pacemaker lead.

Further details associated with cardiac physiology and the operation of the heart as controlled or monitored by a pacemaker may be found in U.S. Pat. No. 4,712,555, to Thornander et al., which patent was incorporated by reference above.

Referring now to FIG. 1, a simplified block diagram of a dual chamber pacemaker 10 is illustrated. The pacemaker 10 is coupled to a heart 12 by way of leads 14 and 16, the lead 14 having an electrode 15 which is in contact with one of the atria of the heart, and the lead 16 having an electrode 17 which is in contact with one of the ventricles of the heart. The leads 14 and 16 carry stimulating pulses to the electrodes 15 and 17, respectively, from an atrial pulse generator (A-PG) 18 and a ventricular pulse generator (V-PG) 20, respectively.

Further, electrical signals from the atria are carried from the electrode 15, through the lead 14, to the input terminal of an atrial channel sense amplifier (P-AMP) 22. Electrical signals from the ventricles are carried from the electrode 17, through the lead 16, to the input terminal of a ventricular sense channel amplifier (R-AMP) 24.

Controlling the dual chamber pacer 10 is a control system 26. The control system 26 receives the output signals from the atrial amplifier 22 over a signal line 28. Similarly, the control system 26 receives the output signals from the ventricular amplifier 20 over a signal line 30. These output signals are generated each time that a P-wave or an R-wave is sensed within the heart 12.

The control system 26 also generates trigger signals which are sent to the atrial pulse generator 18 and the ventricular pulse generator 20 over two signal lines 32 and 34, respectively. These trigger signals are generated each time that a stimulation pulse is to be generated by the respective pulse generator 18 or 20. The atrial trigger signal is referred to simply as the "A-pulse", and the ventricular trigger signal is referred to as the "V-pulse".

During the time that either an A-pulse or V-pulse is being delivered to the heart, the corresponding amplifier, P-AMP 22 or R-AMP 24, is typically disabled by way of a blanking signal presented to these amplifiers from the control system over signal lines 36 and 38, respectively. This blanking action prevents the amplifiers 22 and 24 from becoming saturated from the relatively large stimulation pulses which are present at their input terminals during this time. This blanking action also helps prevent residual electrical signals present in the muscle tissue as a result of the pacer stimulation from being interpreted as P-waves or R-waves.

Still referring to FIG. 1, the pacer 10 also includes a memory circuit 40 which is coupled to the control system 26 by a suitable data/address bus 42. This memory circuit 40 allows certain control parameters, used by the control system 26 in controlling the operation of the pacemaker, to be programmably stored and modified, as required, in order to customize the operation of the pacer 10 to suit the needs of a particular patient. Further, data sensed during the operation of the pacer 10 may be stored in the memory 40 for later retrieval and analysis.

A telemetry circuit 44 is further included in the pacer 10. This telemetry circuit 44 is connected to the control system 26 by way of a suitable command/data bus 46. In turn, the telemetry circuit 44, which is included within the implantable pacer 10, may be selectively coupled to an external programming device 48 by means of an appropriate communication link 50, which communication link 50 may be any suitable electromagnetic link, such as an RF (radio frequency) channel.

Advantageously, through the external programmer 48 and the communication link 50, desired commands may be sent to the control system 26. Similarly, through this communication link 50 and the programmer 48, data (either held within the control system 26, as in a data latch, or stored within the memory 40,) may be remotely received from the pacer 10. In this manner, non-invasive communications may be established with the implanted pacer 10 from a remote, non-implanted, location.

The pacer 10 in FIG. 1 is referred to as a dual chamber pacemaker because it interfaces with both the atria and the ventricles of the heart. Those portions of the pacer 10 which interface with the atria, e.g., the lead 14, the P-wave sense amplifier 22, the A-pulse generator 18, and corresponding portions of the control system 26, are commonly referred to as the atrial channel. Similarly, those portions of the pacer 10 which interface with the ventricles, e.g., the lead 16, the R-wave sense amplifier 24, the V-pulse generator 20, and corresponding portions of the control system 26, are commonly referred to as the ventricular channel.

In accordance with one embodiment of the present invention, the pacemaker 10 further includes a physiological sensor 52 which is connected to the control system 26 of the pacer over a suitable connection line 54. While this sensor 52 is illustrated in FIG. 1 as being included within the pacer 10, it is to be understood that the sensor 52 may also be external to the pacer 10, yet still be implanted within or carried by the patient.

A common type of sensor 52 is an activity sensor, such as a piezoelectric crystal, which is mounted to the can or case of the pacemaker. Other types of physiologic sensors are also known, such as sensors which sense the oxygen content of blood, respiration rate, pH of blood, body motion, and the like. The type of sensor used is not critical to the present invention. Any sensor which is capable of sensing some physiological parameter which is relatable to the rate at which the heart should be beating may be used.

Such sensors are commonly used with "rate-responsive" pacemakers in order to adjust the rate (escape interval) of the pacer in a manner which tracks the physiological needs of the patient. In accordance with one embodiment of the present invention, the sensor 26 is used to control the escape interval or pacing rate of the pacer 10 when the pacer 10 is operating in an alternate mode of operation other than an atrial rate based mode of operation. This is described more fully below in connection with the description of FIG. 4A.

Referring next to FIG. 2, a block diagram of one embodiment of the control system 26 of the pacer 10 is illustrated. It is noted that other embodiments of a control system 26 may also be utilized, such as a microprocessor-based control system. A representative microprocessor-based system is described, for example, in copending U.S. patent application No. 07/301,934, filed Jan. 25, 1989, entitled "Microprocessor Controlled Rate-Responsive Pacemaker Having Automatic Rate Response Threshold Adjustment", assigned to the same assignee as is the present application. This patent application is hereby incorporated herein by reference.

The control system shown in FIG. 2 is based on a state machine wherein a set of state registers 60 define the particular state of the pacer 10 at any instant in time. In general, and as an overview of state machine operation, each state, by design, causes a certain activity or function to be carried out. Several states are executed in a sequence during a given cardiac cycle. The sequence of states which is executed in a particular cardiac cycle is determined by the particular events which occur, such as the sensing of a P-wave or an R-wave, as well as the current state, as certain states can only be entered from certain other states.

Only one state may exist at any instant of time, although several different state machines (or control systems) may operate in parallel to control diverse functions. For example, the telemetry circuit 44 (FIG. 1) preferably utilizes its own state machine, such as is described in the above-cited copending patent application. This telemetry circuit state machine operates essentially independently of the control system state machine shown in FIG. 2.

At the heart of the control system 26 is the state logic 62. It is the state logic which controls the "state" of the state registers 60, and hence the function or operation which will next be carried out by the system. The state logic 62 receives as inputs the current state of the state registers 60, made available over a state bus 64 (which state bus 64 directs the state of the system to several sections of the control system), as well as other signals indicating the current status of the system or events which have occurred.

The output signals from the P-AMP 22 (FIG. 1) and the R-AMP 24 (FIG. 1) are directed to an input decode logic circuit 66. The input decode logic circuit 66 generates appropriate logic signals "IPW" (Inhibiting P-Wave) and "IRW" (Inhibiting R-Wave) which are selected by a multiplexer 68 and sent to rate-determining logic 70. These signals are also sent to the state logic 62. The function of the rate-determining logic 70 is to determine the rate at which either the IPW or IRW signals are occurring.

A signal representative of this rate is sent, as an output signal from the rate determining logic 70, to the state logic 62 over a signal line 72. The rate-determining logic 70 further receives a sensor rate signal from the sensor 52 (FIG. 1), and (depending upon the particular state of the system, as defined by the state registers 60, and as made available to the rate-determining logic 70 over the state bus 64) sends a rate signal to the state logic 62 over signal line 72 indicative of this sensor rate.

Still referring to FIG. 2, a memory control circuit 74 provides the needed interface between the circuits of the control system 26 and the memory 40 (FIG. 1). This memory control circuit 74 may be any conventional memory access circuit which sends or receives data to or from memory at a specified address. Data retrieved from the memory 40 may be sent to either the state logic 62 over signal line(s) 75 or to a programmable timer 76 over a signal line(s) 77. Data sent to the memory 40 may be either the current state of the system (obtained off of the state bus 64), or other selected signals from the state logic 62 (as made available over signal line(s) 73).

The function of the programmable timer 76 is to define a prescribed time interval, the length of which is set by the signal(s) received from the memory control 74 over the signal line(s) 77, and the starting point of which begins coincident with the start of the current state, as obtained from the state bus 64. The timer 76 further generates a time-out (T.O.) signal when this prescribed time interval has elapsed.

During this prescribed time interval, the timing function may be reset by a reset signal, typically obtained from the input decode logic 66, although some states (as obtained from the state bus 64) may also effectuate an immediate reset of the timer 76. The time-out signal is sent to a time-out decode logic 78. It is the function of the time-out decode logic 78 to generate the appropriate trigger signals which are sent to the A-pulse generator 18 or the V-pulse generator 20 (FIG. 1). Further, an appropriate logic signal(s) is sent to the state logic 62 by the time-out decode logic 78 over the signal line(s) 80 in order to notify the state logic 62 that the respective trigger signals have been generated.

An oscillator 82, preferably a crystal-controlled oscillator, generates a basic clock signal C0 which controls the operation of the system logic. This clock signal C0 is sent to clock logic circuits 84, where other appropriate clock signals, such as clock signals C1, C2, and C3, are generated, all derived from the basic clock signal C0. These clock signals are distributed throughout the control system 26 in order to appropriately synchronize the various events and state changes which occur within the pacemaker.

The rate of the basic clock signal C0 is not critical to the present invention. In general, a rate of 25-40 Khz for the basic clock rate C0 is adequate. This rate provides a basic time increment of 25-40 microseconds each clock cycle, and this is more than enough time to effectively control the pacemaker operation. If desired, a faster basic clock rate may be used, particularly by the memory control 74, to speed up the data transfer between the control system 26 and the memory 40, although for most pacemaker operations, a fast data transfer rate is not essential.

In operation, the control system of FIG. 2 starts at an initial state, wherein the state registers 60 assume a prescribed value which defines the initial state. For example, assuming four flip-flops are used for the state registers 60, an initial state might be "1000" (hexadecimal "8") wherein the first flip-flop assumes a "1" state, and the remaining three flip-flops each assume a "0" state. This state may be defined as a V-A Delay (VAD) state wherein a prescribed VA interval is initiated. This interval may be considered as the "escape interval" mentioned previously.

As soon as the memory control 74 detects that the VAD state has been initiated, as evidenced by the "1000" appearing on the state bus 64, it retrieves from the memory 40 an appropriate data word, previously programmed into the memory 40 from the external programmer 48, which defines the desired length of the V-A delay. This data word is sent to the programmable timer and sets the length of the time period which is to be measured during the VAD state.

The timer 76 is essentially just a counter which counts down (or counts up), using a specified clock signal, to the value specified in the data word. When the counting has been completed, and assuming that the counter has not been reset by the occurrence of a P-wave or an R-wave, the counter or timer 76 is said to have "timed-out", and an appropriate time-out signal is generated which is sent to the time-out decode logic 78.

The decode logic 78, in turn, recognizes that the current state of the system is the VAD state (as determined by monitoring the state bus 64), and therefore that the VA interval (escape interval) has timed out without any cardiac activity having been sensed, generates an A-pulse trigger signal, sent to the A-pulse generator 18, so that the atrium can be stimulated. At the same time, an appropriate logic signal(s) is sent to the state logic 62 over the signal line(s) 80 to alert the state logic to the fact that the timer 76 has timed out.

The state logic 62, in response to receiving the signal(s) from the time-out decode logic 78, and also in response to the current VAD state, triggers the next state of the prescribed sequence. For DDD operation, this state is typically a blanking state, or BLANK state, during which the P and R sense amplifiers, 22 and 24, are disabled. Accordingly, the state logic generates appropriate signal(s) on signal lines 36 and 38 to blank the P-wave sense amplifier 22 and the R-wave sense amplifier 24, respectively, and also causes the state registers 60 to change to a BLANK state, which state could be defined, for example, by the flip-flops of the state registers 62 assuming a "0001" (hex "1") condition.

This BLANK state, detected on the state bus 64, causes the memory control circuitry 74 to retrieve an appropriate data word from the memory 40 which defines the length of the blanking interval, which data word is loaded into the programmable timer 76. As soon as the timer 76 times out, indicating that the prescribed blanking interval has elapsed, a time-out signal is generated which is sent to the time-out decode logic 78. Upon receipt of this time-out signal, and in response to the current state being a BLANK state, the time-out decode logic 78 sends an appropriate logic signal to the state logic 62. The state logic 62 responds by steering the state registers 62 to assume the next state in the prescribed sequence, which may be, for example, an A-V Delay (AVD) state.

At the beginning of the AVD state, another value is loaded into the programmable timer 76 which defines the length of the AV interval. If the timer 76 times out without being reset, indicating that no P-waves or R-waves have been sensed, the decode logic 78 generates a V-pulse trigger signal, and notifies the state logic 62 of this event. The state logic 62, in turn, causes the next appropriate state to be entered, which state may be another blanking state, or BLANK state, similar to the one described above, but having perhaps a different duration. At the conclusion or timing out of this second BLANK state, the next state in the prescribed sequence is initiated, which state may be a refractory (REF) state.

In the manner described above, the control system 26 assumes one state after another, thereby controlling the operation of the pacemaker 10. In general, a state is changed when the timer 76 times out, or when a prescribed event occurs. For example, if during the VAD state an IPW signal is received (indicating that a P-wave has been sensed), the input decode logic 66 generates a reset signal to reset the timer 76, and the state logic 62 responds by immediately (typically within the next few clock cycles) changing the state to the next appropriate state, for example, an AVD state.

Further, if during the AVD state an IRW signal is received (indicating that an R-wave has been sensed), the input decode logic 66 generates another reset signal to reset the timer 76, and the state logic responds by immediately changing the state to the next appropriate state, for example, a refractory (REF) state. It is noted that the state of the control system 26 could also be changed by receipt of an appropriate command from the telemetry system.

The control system 26 of FIG. 2 may be realized using dedicated hardware circuits, or by using a combination of hardware and software (or firmware) circuits. The appropriate sequence of states for a given mode of operation, such as DDD or VVI, for example, may be defined by appropriate control of the memory control 74 and the state logic 62. These circuit elements, in turn, are most easily controlled through an appropriate software or firmware program which is placed or programmed into the pacemaker memory circuits. The manner of accomplishing such programming is well known in the art.

A detailed description of the various circuits of the control system 26 of FIG. 2 will not be presented herein because all such circuits may be conventional, or may be patterned after known circuits available in the art. Reference is made, for example, to the above incorporated by reference U.S. Pat. No. 4,712,555, to Thornander et al., wherein a state-machine type of operation for a pacemaker is described; and to U.S. Pat. No. 4,788,980, to Buchanan et al., wherein the various timing intervals used within the pacemaker and their interrelationship are more thoroughly described.

It is noted that a dual chamber programmable pacemaker may have up to eighteen states associated with its control system. These states are described fully in the above-referenced patent application. A summary of these states is presented below in Table 1.

              TABLE 1______________________________________States of the Pacemaker Control SystemState  Symbol       Description______________________________________0      APW        A-Pulse (A-Pulse triggered)1      BLANK      V-Sense Input Inhibit (Blank)2      AREF       A Refractory3      SIPW       Sensed Inhibiting P-wave (P-wave             sensed)4      AVD        A-V Delay5      CROSS      Crosstalk Sense6      VPW        V-Pulse (V-Pulse triggered)7      STRW       Sensed Inhibiting R-wave (R-wave             sensed)8      VAD        V-A Delay9      SHORT1     Shorten A-V Delay a first             prescribed amount if IPW during             SHORT1 with Physiologic A-V             Delay OnA      MTR        Max Track RateB      SHORT2     Shorten A-V Delay a second             prescribed amount if IPW during             SHORT2 with physiologic A-V             Delay OnC      RRT        Lengthen VA interval if at low             batteryD      RNOISE     R Noise sensed during VREF or             RNOISEE      LIPW       Latched IPW - P-wave sensed in             MTRF      PNOISE     P Noise sensed during AREF or             PNOISE(none) VREF       V Refractory, independent 1-bit             state machine synchronized to             pulse generator when AREF starts(none) ABSREF     Absolute Refractory for a             prescribed period, starts when             AREF starts______________________________________

In addition to the states identified in Table 1, the present invention preferably incorporates two additional states: (1) an ARC (Atrial Rate Check) state, and an ARV (Atrial Rate Verify) state. At least the ARV state is preferably defined by an independent 1-bit state machine which operates in parallel with the system state machine.

The operation of the pacemaker control system 26 of FIGS. 1 and 2 as it relates to the present invention may be better understood by reference to the state diagram of FIG. 3. The state diagram of FIG. 3 illustrates in each circle a particular state which the system may assume. The connecting lines between the circles illustrate the various events which may cause the state to change.

Before explaining FIG. 3, however, it should be emphasized that FIG. 3 depicts a simplified state diagram. That is, for purposes of clarity only a portion of the states shown in Table 1 are used by the pacemaker represented by FIG. 3. Further, some of the states which may be used in the pacemaker, as identified in Table 1, such as the absolute refractory state, ABSREF, the ventricular refractory state, VREF, and the atrial refractory state, AREF, are combined in the pacemaker state diagram of FIG. 3 as simply a refractory state, REF. This is done for simplicity of explanation because the various responses which may be taken by the pacemaker during the AREF or VREF states, for example, to better distinguish noise from other events, may remain unchanged for the present invention.

In other words, for purposes of understanding the present invention it is sufficient to assume that during a refractory period or state no action is taken until the refractory state, REF, times out, and the next state is entered. Other states identified in Table 1, such as the CROSS, RRT, RNOISE, LIPW, SHORT1 and SHORT2 states are not included in the description which follows because they play no part in the invention. In fact, for purposes of the present invention, a pacemaker may function without these states.

Other states shown in Table 1, such as the SIPW and SIRW states, are referred to in the state diagram of FIG. 3 as "events" (IPW and IRW) which simply trigger the state of the control system to shift from one state to another. In practice, a logic designer may choose to define a temporary state, such as an SIPW or SIRW state, to indicate that a P-wave or an R-wave has been detected by receipt of an IPW or IRW signal. However, for purposes of understanding the present invention, it is sufficient to simply recognize that the sensing of a P-wave (IPW) or the sensing of an R-wave (IRW) is an event which can affect (change) the state of the control system.

Referring then to the state diagram of FIG. 3, the operation of the present invention will be described. As has been indicated, the present invention is directed to a particular manner of controlling or operating a pacemaker which is operating in an atrial rate based mode, such as DDD. The bracketed portion 90 of FIG. 3 essentially represents a simplified state diagram of a DDD pacer. That is, a VAD state is entered.

If a timeout occurs without a P-wave being sensed, then an APW state is entered during which an A-pulse is delivered to the atrium, followed by a BLANK state, followed by an AVD state. If the AVD state times out without an R-wave being sensed, then a VPW state is entered during which a V-pulse is delivered to the ventricle, followed by a BLANK state, followed by a refractory, or REF, state, followed by a maximum tracking rate (MTR) state. If the MTR state times out without a P-wave being sensed, then the VAD state is reinitiated.

Assuming that no P-waves or R-waves are sensed, the above cycle repeats itself with an A-pulse being generated after every VAD state and a V-pulse being generated after every AVD state. Notice that the MTR state assures that these stimulation pulses will not be delivered at a rate which exceeds a maximum upper limit (which upper limit is programmable). That is, the MTR state inserts a known time delay into the sequence of states which separates the A-pulse and the V-pulse by a set time period. In effect, this set time period defines a maximum upper rate limit (URL) at which the heart can be paced by the pacemaker. Advantageously, this set time period can be programmed to any desired value, thereby allowing the URL to be programmably selected.

In accordance with conventional DDD operation, if a P-wave is sensed (IPW) during either the VAD or MTR states, the AVD state is entered. The present invention modifies this operation by inserting an intermediate state, identified as an ARC (Atrial Rate Check) state, into the sequence. The ARC state is entered upon the occurrence of an IPW. During the ARC state, the atrial rate is checked or measured. This operation is carried out by the rate-determining logic 70 of FIG. 2, or its equivalent.

If the rate is below a prescribed threshold limit, hereafter a tachycardia rate limit (TRL), then the AVD state is entered, and the normal DDD operation continues. This tachycardia rate limit, or TRL, is set at a rate higher than the maximum upper rate limit, or URL, of the pacemaker. Thus, the ARC state is entered (that is, the atrial rate is checked or measured) even when the pacer is stimulating the heart at the URL. If during the ARC state a determination is made that the atrial rate exceeds the TRL (identified in FIG. 3 as a "HIGH" event), then an atrial rate verify (ARV) state is entered during which the atrial rate continues to be monitored.

The ARV state is maintained for so long as the atrial rate remains above a third prescribed rate threshold, referred to as T3 herein. The sensing that the atrial rate exceeds T3 during the ARV state is identified in FIG. 3 as a "HIGH" event.

During the ARV state, the pacemaker switches from the DDD mode of operation to an alternate mode of operation. This alternate mode of operation is preferably a non-atrial rate based mode, such as VVI. The bracketed portion 92 of the state diagram of FIG. 3 represents a simplified state diagram of a VVI pacer. So long as the pacer remains in the ARV state, the VVI mode (or other desired mode) is enabled and the pacer functions in a conventional VVI fashion (or other desired mode).

However, in the event a determination is made in the ARV state that the atrial rate has decreased to an acceptable level (which event is identified in FIG. 3 as a "PASS" event), that is, to a level less than the threshold T3, then the pacemaker switches back to operate in the initial atrial rate based mode.

The above operation is further illustrated in the flow chart of FIG. 4A. As seen in FIG. 4A, the DDD mode of operation is initialized at block 94. During the normal DDD operation, a determination is made as to whether a P-wave has been sensed (block 96). If not, a determination is made as to whether the atrial channel sensitivity needs to be adjusted, as shown in the block diagram of FIG. 4B, explained below. If a P-wave is sensed, a determination is next made (block 98) as to whether the atrial rate (P-wave rate) exceeds a first rate limit threshold, T1, which first rate limit is the upper rate limit (URL) of the pacemaker.

This operation is carried out by the rate-determining logic 70 (FIG. 2) using any suitable technique. Typically, atrial rate is determined by simply measuring the period or interval between successive P-waves, as described for example in U.S. Pat. No. 4,722,341, to Hedberg et al. Preferably, however, in accordance with the present invention, several P-waves are monitored, and an average P-rate value is obtained, or other rate measuring techniques are used (such as maintaining a running average of the P-waves over the last several cycles), thereby filtering out any abnormal or one-of-a-kind fast P-waves that may occasionally occur.

If the P-wave rate is less than the first threshold rate limit, T1, then the pacemaker continues to operate in conventional DDD fashion (cycling back through block 100). If, however, the determination made at block 98 indicates that the atrial rate exceeds the first rate threshold T1, a second determination is made (block 102) as to whether the atrial rate exceeds a second rate threshold value, T2. This second rate threshold T2 may be thought of as a tachycardia rate limit (TRL), and represents a programmable value indicative of the maximum P-wave rate that will be tolerated for a particular patient before action is taken to stop the fast atrial rate.

If the atrial rate is less than the TRL, or T2, then the pacer continues to pace at the URL (block 104), and the P-wave continues to be monitored (cycling through block 106). If, however, a determination is made at block 102 that the atrial rate exceeds the TRL, then the pacer mode is switched from DDD to an alternate mode of operation (block 114), such as VVI or VVT.

Before switching to the alternate mode of operation, a determination is also made (block 108) as to whether an activity sensor, such as the sensor 52 (FIG. 2), is to be used with the pacer during its alternate mode of operation. If so, the sensor is enabled (block 110) and the control system of the pacemaker is modified appropriately so as to be controlled exclusively by the sensor (block 112). That is, the sensor provides a rate-determining signal which sets the value of the escape interval or pacing interval used by the pacer during its alternate mode of operation. In this manner, the pacer can better attempt to bring the heart under control by providing stimulation pulses only as dictated by the sensor, not as dictated by the arrhythmatic heart.

After the pacer has been switched to operate in the alternative mode of operation (block 114), the pacer continues to operate in this mode in conventional manner at the same time that the atrial rate is monitored (block 116). Periodically, e.g., every cardiac cycle, or every n cardiac cycles, where n is an integer greater than one, the atrial rate is again checked (block 118). If a determination is made that the atrial rate has dropped below a third prescribed rate threshold, T3, then the pacer is switched back to its initial atrial rate based mode of operation (block 94).

The pacer continues to operate in this initial mode in accordance with the process described above, that is, as indicated by the flow chart of FIG. 4A. If the determination made at block 118 indicates that the atrial rate has not dropped below the threshold T3, then the pacer continues to operate in the alternate mode of operation (block 116) in a conventional manner, except that the atrial rate continues to be monitored. During this time, the pacer is in the ARV state, as described above in connection with the state diagram of FIG. 3.

Typical values for the rate threshold limits T1, T2 and T3 may be on the order of 150-180 bpm for T1, 200-230 bpm for T2, and 100-150 bpm for T3.

Referring next to FIG. 4B, another feature of the present invention will be described. In the preferred embodiment of the present invention, this feature is included within the same pacer as are the mode switching features of FIG. 4A, and hence FIG. 4B is drawn as a continuation or extension of the flow chart of FIG. 4A. As previously indicated, sometimes it is the pacer's inability to sense a P-wave while operating in an atrial rate based mode which gives rise to a cardiac arrhythmia. Hence, it is desirable to determine whether P-waves are being sensed and, if not, to adjust the sensitivity of the P-wave sense amplifier so that they can be sensed. Thus, in FIG. 4A, one of the first determinations which is made (block 96) is whether a P-wave is sensed. If not, then the process described in FIG. 4B is invoked.

Upon entering the process of FIG. 4B, a decision is initially made as to whether the A-channel sensitivity is to be verified (block 120). This block is present in the flow chart simply to emphasize that A-channel sensitivity verification may be a selectable option programmed into the pacemaker. If the option is off--if the atrial channel sensitivity is not to be verified--then the process simply returns back to FIG. 4A and conventional DDD operation continues (block 100). If the option is on, then the pacer mode is switched to a test/verify mode (block 122).

In accordance with this special test/verify mode, the atrial channel is monitored for a prescribed period of time (block 124), such as 5-10 seconds, to determine if any P-waves are sensed (block 126). If P-waves are sensed, then the process makes a determination whether the test should be performed again (block 128). This determination (to test again) is preferably an option which can be programmed into the pacemaker at implant and later modified, as required, by the physician. For example, it may be desirable for a given patient to monitor the atrium for the prescribed period of time (block 124) for several consecutive time periods, e.g. five periods of 5-10 seconds each.

If a P-wave is regularly sensed during all of these time periods, then a final decision can be made at block 128 to terminate the test/verify mode. In such case, the pacer mode is switched back to DDD, or another initial atrial rate based mode, (through block 130) and the normal operation of the pacer for that mode continues (block 100). If however, a P-wave is not sensed during the prescribed time period, or is not regularly sensed during all of the time periods during which the test is performed, than such is an indication that the A-channel sensitivity probably needs to be adjusted.

It is noted that "atrial channel sensitivity" refers to the ability of the P-wave sense amplifier 22, FIG. 1, to sense P-waves. By adjusting the gain of this amplifier, which adjustment can be made using techniques known in the art, the magnitude of the P-waves which are detected by the amplifier may be optimally set.

Accordingly, for the case where P-waves are not being sensed, the sensitivity of the atrial sense amplifier is adjusted by a prescribed increment (block 132). Sensitivity settings are typically measured in millivolts, and this incremental adjustment is preferably on the order of 0.1-0.3 millivolts per increment. After making this incremental adjustment, another determination is made (block 134) as to whether P-waves are being sensed. If so, then this new sensitivity is maintained (block 136), the pacer is switched back to the DDD or other atrial rate based mode (block 138), and the normal operation of the pacer continues for that mode (block 100).

Where P-waves are not sensed at block 134, even after the sensitivity has been adjusted by the specified incremental amount, a determination is made as to whether further incremental adjustments of the sensitivity are possible (block 140). If so, then the next incremental adjustment is made and the process continues until a P-wave is sensed. If not, i.e., if there is no further adjustment range possible, then a major failure of the atrial channel exists, and the pacer immediately ceases its efforts to monitor P-waves and instead switches to monitoring R-waves (block 142).

If the R-wave rate is determined to be above a prescribed threshold (block 144), for example, above the TRL, then the heart is still experiencing a tachycardia or other arrhythmia and the pacer mode is immediately switched to a different mode of operation (block 146), as required, in order to break the tachycardia and to provide the safest possible mode of operation for the patient. For example, a VOO mode may be initiated (ventricular pacing, no sensing).

This "safe" mode of operation continues (block 148) until a reprogramming command is received (block 150). Operation of the pacer in this new "safe" mode advantageously alerts the physician (who is the only one who can effectuate a reprogramming change) as to the difficulties the pacer had in sensing P-waves, and the arrhythmias that were experienced by the patient. The physician may then determine an appropriate course of action, e.g., reprogram to a still different mode of operation (block 154), perform additional tests, or the like.

At the point in the process where the R-wave rate is tested (block 144), if it is determined that the R-wave rate is not greater than the prescribed threshold, then the heart is probably not experiencing an arrhythmia, and any desired mode of operation can be initiated by the pacemaker (block 152), such as a VVI or VVT mode. This mode continues (block 148) until a new reprogramming command is received (block 150).

As described above, the present invention thus provides a pacer which provides all the advantages of atrial rate based pacing, but which also avoids some of the problems associated with atrial rate based pacing in the event an atrial arrhythmia condition develops. More particularly, if the atrial rate exceeds a prescribed upper rate limit, T2, then the pacer is switched automatically to a non atrial rate based mode.

Further, during this non-atrial rate based pacing mode, the rate of the pacer is controlled by a physiological sensor, such as an activity sensor. As soon as the atrial rate falls below another prescribed rate threshold, T3, then the pacing mode automatically switches back to the initial atrial rate based mode. Moreover, the pacer includes means for automatically adjusting the sensitivity of the atrial channel in the event P-waves are not consistently sensed.

It should be noted that the automatic adjusting procedures described herein for adjusting the atrial channel may be used to adjust the atrial channel sensitivity in either direction, thereby allowing an optimum value of sensitivity to be automatically maintained.

Although an exemplary embodiment of the present invention has been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. All such changes, modifications, and alterations should therefore be seen as within the scope of the present invention. Accordingly, the complete scope of the present invention should be determined with reference to the claims set forth below.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4305396 *Apr 16, 1979Dec 15, 1981Vitatron Medical B.V.Rate adaptive pacemaker and method of cardiac pacing
US4712556 *Sep 25, 1985Dec 15, 1987Intermedics, Inc.Pacemaker and method for ventricular rate limit operation and termination of pacemaker mediated tachycardia
US4830006 *Jun 17, 1986May 16, 1989Intermedics, Inc.Implantable cardiac stimulator for detection and treatment of ventricular arrhythmias
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5074308 *Sep 26, 1990Dec 24, 1991Siemens-Pacesetter, Inc.System and method for recognizing pacemaker-mediated tachycardia
US5107850 *Nov 2, 1990Apr 28, 1992Cardiac Pacemakers, Inc.Method and apparatus for classifying and treating cardiac arrhythmias based on atrial and ventricular activity
US5184614 *Oct 19, 1990Feb 9, 1993Telectronics Pacing Systems, Inc.Implantable haemodynamically responsive cardioverting/defibrillating pacemaker
US5226415 *Nov 22, 1991Jul 13, 1993Ela MedicalMethod and apparatus for controlling a dual-chamber pacemaker in response to physiological and pathological atrial events
US5228438 *Oct 8, 1991Jul 20, 1993Siemens Pacesetter, Inc.Implantable pacemaker including means and method of terminating a pacemaker-mediated tachycardia during rate adaptive pacing
US5237992 *Mar 5, 1992Aug 24, 1993Siemens Pacesetter, Inc.Implantable pacemaker providing hysteresis in dual-chamber modes
US5269299 *Aug 5, 1991Dec 14, 1993Siemens Pacesetter, Inc.System and method for preventing atrial competition during sensor-driven operation of a dual-chamber pacemaker
US5318594 *Dec 24, 1991Jun 7, 1994Ela MedicalDDD type cardiac pacemaker having automatic operating mode switching
US5334220 *Nov 13, 1992Aug 2, 1994Siemens Pacesetter, Inc.Dual-chamber implantable pacemaker having an adaptive AV interval that prevents ventricular fusion beats and method of operating same
US5340361 *Nov 13, 1992Aug 23, 1994Siemens Pacesetter, Inc.Implantable pacemaker having adaptive AV interval adoptively shortened to assure ventricular pacing
US5342405 *Nov 19, 1992Aug 30, 1994Siemens Pacesetter, Inc.System and method for selecting a mode of operation of a dual-chamber pacemaker
US5350401 *Mar 26, 1993Sep 27, 1994Siemens Pacesetter, Inc.Implantable cardioverter/defibrillator device having means for determining and treating low amplitude ventricular fibrillation and method thereof
US5374281 *Feb 9, 1993Dec 20, 1994Siemens Pacesetter, Inc.Hysteresis in a rate-responsive pacemaker
US5417714 *May 11, 1993May 23, 1995Pacesetter, Inc.DDI pacing with PVC-protected hysteresis and automatic AV interval adjustment
US5423869 *Jan 21, 1993Jun 13, 1995Pacesetter, Inc.Multi-sensor rate-responsive pacemaker and method of operating same
US5507783 *Jan 11, 1995Apr 16, 1996Pacesetter, Inc.Pacemaker mediated tachycardia response for VDD and VDDR modalities
US5514164 *Mar 25, 1994May 7, 1996Pacesetter, Inc.DDD pacing response to atrial tachyucardia and retrograde conduction
US5549649 *Jun 10, 1994Aug 27, 1996Pacesetter, Inc.Programmable pacemaker including an atrial rate filter for deriving a filtered atrial rate used for switching pacing modes
US5607458 *Jul 13, 1995Mar 4, 1997Pacesetter, Inc.Safety optimization in microprocessor controlled implantable devices
US5713928 *Jul 25, 1996Feb 3, 1998Ela MedicalProcess of controlling a dual chamber cardiac pacemaker
US5724985 *Aug 2, 1995Mar 10, 1998Pacesetter, Inc.User interface for an implantable medical device using an integrated digitizer display screen
US5741308 *May 15, 1995Apr 21, 1998Pacesetter, Inc.Dual-chamber implantable pacemaker and method of operating same for automatically setting the pacemaker's AV interval as a function of a natural measured conduction time
US5766229 *Apr 14, 1997Jun 16, 1998Pacesetter, Inc.Capture verification method and apparatus for implantable pacemaker utilizing heart rhythm stability measurements to minimize the likelihood of fusion
US5788717 *Jul 11, 1995Aug 4, 1998Pacesetter, Inc.Atrial rate determination and atrial tachycardia detection in a dual-chamber implantable pacemaker
US5792201 *Nov 15, 1996Aug 11, 1998Pacesetter, Inc.Implantable cardiac stimulating device
US5814077 *May 12, 1997Sep 29, 1998Pacesetter, Inc.Pacemaker and method of operating same that provides functional atrial cardiac pacing with ventricular support
US5836989 *Dec 26, 1996Nov 17, 1998Medtronic, Inc.Method and apparatus for controlling an implanted medical device in a time-dependent manner
US5873895 *Aug 3, 1998Feb 23, 1999Pacesetter, Inc.Pacemaker and method of operating same that provides functional atrial cardiac pacing with ventricular support
US5893882 *Dec 17, 1996Apr 13, 1999Medtronic, Inc.Method and apparatus for diagnosis and treatment of arrhythmias
US5899928 *May 6, 1997May 4, 1999Pacesetter, Inc.Descriptive transtelephonic pacing intervals for use by an emplantable pacemaker
US5931856 *Nov 21, 1997Aug 3, 1999Ela Medical S.A.Active implantable medical device having dual chamber cardiac stimulation and a fallback mode
US5974341 *Dec 22, 1997Oct 26, 1999Pacesetter, Inc.Method and apparatus for detecting and displaying diagnostic information in conjunction with intracardiac electrograms and surface electrocardiograms
US5989199 *Nov 27, 1996Nov 23, 1999Assurance Medical, Inc.Tissue examination
US6058328 *Jan 24, 1997May 2, 2000Pacesetter, Inc.Implantable stimulation device having means for operating in a preemptive pacing mode to prevent tachyarrhythmias and method thereof
US6063031 *Oct 14, 1997May 16, 2000Assurance Medical, Inc.Diagnosis and treatment of tissue with instruments
US6067470 *Mar 5, 1998May 23, 2000Mower Family Chf Treatment Irrevocable TrustSystem and method for multiple site biphasic stimulation to revert ventricular arrhythmias
US6081747 *Nov 23, 1998Jun 27, 2000Pacesetter, Inc.Dual-chamber implantable pacemaker having negative AV/PV hysteresis and ectopic discrimination
US6091981 *Sep 16, 1997Jul 18, 2000Assurance Medical Inc.Clinical tissue examination
US6101415 *Dec 22, 1997Aug 8, 2000Pacesetter, Inc.Method and apparatus for detecting and displaying diagnostic information for an implantable medical device
US6101416 *Jul 29, 1998Aug 8, 2000Pacesetter, Inc.System and method for atrial autocapture in single-chamber pacemaker modes using far-field detection
US6122546 *Aug 3, 1998Sep 19, 2000Pacesetter, Inc.Pacemaker and method of operating same that provides functional atrial cardiac pacing with ventricular support
US6128533 *Mar 22, 1999Oct 3, 2000Pacesetter, Inc.Pacemaker with automatic PVARP adjustment during automatic mode switching
US6178351Jan 11, 1999Jan 23, 2001The Mower Family Chf Treatment Irrevocable TrustAtrial sensing and multiple site stimulation as intervention means for atrial fibrillation
US6243606Aug 18, 1999Jun 5, 2001Pacesetter, Inc.Implantable stimulation device and method for determining atrial autocapture using programmable PVARP
US6259950Sep 14, 1999Jul 10, 2001Pacesetter, Inc.Implantable stimulation device and method for determining a trial autocapture using backup atrial stimulation
US6263244Sep 15, 1999Jul 17, 2001Pacesetter, Inc.Implantable stimulation device and method for determining atrial autocapture using PVC response
US6282444Aug 31, 1999Aug 28, 2001Pacesetter, Inc.Implantable device with electrical infection control
US6301504Oct 8, 1999Oct 9, 2001Pacesetter, Inc.High speed telemetry system using transmission medium as a component of a telemetry link
US6308100Sep 22, 1999Oct 23, 2001Pacesetter, Inc.Method and apparatus for displaying programming events detected by an implantable medical device
US6321115Dec 3, 1999Nov 20, 2001Pacesetter, Inc.Noise detection system and method for use in an implantable medical device
US6334071Jun 7, 1999Dec 25, 2001Pacesetter, Inc.Minute volume pacemakers that require only a single distal electrode
US6337995Nov 13, 2000Jan 8, 2002Mower Chf Treatment Irrevocable TrustAtrial sensing and multiple site stimulation as intervention for atrial fibrillation
US6341235Oct 18, 2000Jan 22, 2002Mower Chf Treatment Irrevocable TrustAugmentation of electrical conduction and contractility by biphasic cardiac pacing administered via the cardiac blood pool
US6343232Oct 19, 2000Jan 29, 2002Mower Chf Treatment Irrevocable TrustAugmentation of muscle contractility by biphasic stimulation
US6363280Oct 15, 1999Mar 26, 2002Pacesetter, Inc.Battery conservation in implantable cardioverter-defibrillators and pacemakers
US6374139Sep 22, 1999Apr 16, 2002Pacesetter, Inc.Method and apparatus for implementing operating changes and displaying operating change information for an implantable medical device
US6389316Jan 11, 2000May 14, 2002Pacesetter, Inc.System and method for automatic atrial capture detection and atrial pacing threshold determination
US6400985Feb 6, 2001Jun 4, 2002Pacesetter, Inc.Method and apparatus for timing events within an implantable medical device
US6400988Feb 18, 2000Jun 4, 2002Pacesetter, Inc.Implantable cardiac device having precision RRT indication
US6400990Feb 18, 2000Jun 4, 2002Pacesetter, Inc.Patient activated telemetry control unit using bidirectional asymmetric dual-mode telemetry link to communicate with an implanted device
US6408210Jan 11, 2000Jun 18, 2002Pacesetter, Inc.System and method for automatic atrial capture detection and atrial pacing threshold determination
US6411845Sep 5, 2000Jun 25, 2002Mower Chf Treatment Irrevocable TrustSystem for multiple site biphasic stimulation to revert ventricular arrhythmias
US6411847Sep 22, 2000Jun 25, 2002Morton M. MowerApparatus for applying cyclic pacing at an average rate just above the intrinsic heart rate
US6424867Sep 30, 1999Jul 23, 2002Pacesetter, Inc.Secure telemetry system and method for an implantable cardiac stimulation device
US6430441Jan 18, 2000Aug 6, 2002Pacesetter, Inc.Implantable cardiac stimulation device having autocapture/autothreshold capability
US6434424Dec 22, 1999Aug 13, 2002Medtronic, Inc.Regularization of ventricular rate during atrial tachyarrhythmia
US6434428Jul 31, 2000Aug 13, 2002Pacesetter, Inc.System and method for optimizing far-field R-wave sensing by switching electrode polarity during atrial capture verification
US6442426Dec 1, 1999Aug 27, 2002Pacesetter, Inc.Implantable ventricular cadioverter-defibrillator employing atrial pacing for preventing a trial fibrillation form ventricular cardioversion and defibrillation shocks
US6445949Jan 5, 2000Sep 3, 2002Pacesetter, Inc.Implantable cardioversion device with a self-adjusting threshold for therapy selection
US6453197Apr 18, 2000Sep 17, 2002Pacesetter, Inc.Implantable cardiac stimulation device including a system for and method of automatically inducing a tachyarrhythmia
US6456876Feb 28, 2000Sep 24, 2002Pacesetter, Inc.Dual-chamber implantable cardiac stimulation system and device with selectable arrhythmia termination electrode configurations and method
US6456879Oct 5, 2000Sep 24, 2002Pacesetter, Inc.Method and device for optimally altering stimulation energy to maintain capture of cardiac tissue
US6456881Aug 2, 2000Sep 24, 2002Pacesetter, Inc.System and method of identifying fusion for dual-chamber automatic capture stimulation device
US6456882Oct 6, 2000Sep 24, 2002Pacesetter, Inc.Implantable cardiac stimulation device having automatic capture/threshold capability using a dynamically adjustable safety margin
US6477416May 15, 2000Nov 5, 2002Pacesetter, Inc.System and method for automatically and adaptively segmenting an atrial blanking period
US6477420Apr 27, 2001Nov 5, 2002Medtronic, IncControl of pacing rate in mode switching implantable medical devices
US6493584Sep 8, 2000Dec 10, 2002Pacesetter, Inc.Implantable cardiac stimulation device and method which discriminates between noise and cardiac activity
US6501987May 26, 2000Dec 31, 2002Cardiac Pacemakers, Inc.Rate smoothing control
US6522925May 13, 2000Feb 18, 2003Cardiac Pacemakers, Inc.System and method for detection enhancement programming
US6532389Aug 15, 2001Mar 11, 2003Pacesetter, Inc.Implantable medical device with single bit upset error detection and correction
US6535763Aug 22, 1999Mar 18, 2003Cardia Pacemakers, Inc.Event marker alignment by inclusion of event marker transmission latency in the real-time data stream
US6539260Feb 28, 2000Mar 25, 2003Pacesetter, Inc.Atrial sensing and pacing using a unipolar atrial electrode
US6549806Oct 5, 2000Apr 15, 2003Pacesetter, Inc.Implantable dual site cardiac stimulation device having independent automatic capture capability
US6553259Mar 14, 2001Apr 22, 2003Pacesetter, Inc.System and method of performing automatic capture in an implantable cardiac stimulation device
US6584354Jul 17, 2001Jun 24, 2003Pacesetter, Inc.Implantable stimulation device and method for determining atrial autocapture using PVC response
US6594523Sep 14, 2001Jul 15, 2003Pacesetter, Inc.Implantable stimulation device, programmer, and method for automatically evaluating interaction of the device with a patient's heart
US6600952May 30, 2002Jul 29, 2003Pacesetter, Inc.Secure telemetry system and method for an implantable cardiac stimulation device
US6604000Dec 8, 2000Aug 5, 2003Pacesetter, Inc.Method and device for responding to the detection of ischemia in cardiac tissue
US6615082Oct 5, 2000Sep 2, 2003Pacesetter, Inc.Method and device for optimally altering stimulation energy to maintain capture of cardiac tissue
US6636765Feb 6, 2001Oct 21, 2003Pacesetter, Inc.Method and apparatus for timing events within an implantable medical device
US6645153Feb 7, 2002Nov 11, 2003Pacesetter, Inc.System and method for evaluating risk of mortality due to congestive heart failure using physiologic sensors
US6654639May 7, 2001Nov 25, 2003Pacesetter, Inc.Method and device for multi-chamber cardiac pacing in response to a tachycardia
US6671548Aug 30, 2000Dec 30, 2003Pacesetter, Inc.Implantable stimulation device and method for discrimination atrial and ventricular arrhythmias
US6694188Dec 12, 2001Feb 17, 2004Pacesetter, Inc.Dynamic control of overdrive pacing based on degree of randomness within heart rate
US6714819Mar 13, 2000Mar 30, 2004Pacesetter, Inc.System and method of automatically adjusting auto capture safety margin
US6721601Mar 19, 2002Apr 13, 2004Pacesetter, Inc.System and method for automatic atrial capture detection and atrial pacing threshold determination
US6738668Nov 1, 2001May 18, 2004Pacesetter, Inc.Implantable cardiac stimulation device having a capture assurance system which minimizes battery current drain and method for operating the same
US6738669Oct 24, 2001May 18, 2004Pacesetter, Inc.System and method for multichamber cardiac stimulation with ventricular capture verification using far-field evoked response
US6763267Jan 22, 2002Jul 13, 2004Cardiac Pacemakers, Inc.Ventricular conduction delay trending system and method
US6766193Oct 11, 2001Jul 20, 2004Pacesetter, Inc.Battery conservation in implantable cardioverter-defibrillators and pacemakers
US6766194Dec 12, 2001Jul 20, 2004Pacesetter, Inc.Dynamic control of overdrive pacing based on degree of randomness within heart rate
US6775571Dec 12, 2001Aug 10, 2004Pacesetter, Inc.Dynamic control of overdrive pacing based on degree of randomness within heart rate
US6782291Sep 5, 2000Aug 24, 2004Pacesetter, Inc.Implantable cardiac stimulation device with automatic evoked response sensing electrode configuration selection and method
US6788971May 17, 2002Sep 7, 2004Pacesetter, Inc.System and method for optimizing far-field r-wave sensing by switching electrode polarity during atrial capture verification
US6832112Dec 28, 2001Dec 14, 2004Pacesetter, Inc.Method of adjusting an AV and/or PV delay to improve hemodynamics and corresponding implantable stimulation device
US6895274Aug 14, 2001May 17, 2005The Mower Family Chf Treatment Irrevocable TrustAntitachycardial pacing
US6904317Jan 9, 2002Jun 7, 2005Pacesetter, Inc.Method and apparatus for dynamically adjusting overdrive pacing parameters
US6904321Jul 29, 2002Jun 7, 2005Pacesetter, Inc.System and method of identifying fusion for dual-chamber automatic capture stimulation device
US6907291Jun 18, 2003Jun 14, 2005Pacesetter, Inc.Secure telemetry system and method for an implantable cardiac stimulation device
US6925329 *Aug 13, 2001Aug 2, 2005Pacesetter, Inc.Automatic setting of cardiac operating parameters based upon capture threshold level
US6928326Mar 31, 2003Aug 9, 2005Pacesetter, Inc.Diagnosis of fusion or pseudofusion
US6934587Jun 3, 2002Aug 23, 2005Pacesetter, IncSystem and method for automatic atrial capture detection and atrial pacing threshold determination
US6941170Sep 25, 2001Sep 6, 2005Pacesetter, Inc.Dynamic adjustment of overdrive pacing rate based on sensor indicated rate
US6950703Jun 8, 2001Sep 27, 2005Pacesetter, Inc.Implantable medical device with single bit upset error detection and correction
US6954672Jun 20, 2002Oct 11, 2005Pacesetter, Inc.Implantable cardiac stimulation device including a system for and method of automatically inducing a tachyarrhythmia
US6957100Dec 26, 2000Oct 18, 2005Cardiac Pacemakers, Inc.Method and system for display of cardiac event intervals in a resynchronization pacemaker
US6959213Nov 21, 2002Oct 25, 2005Intermedics, Inc.Implantable device with digital waveform telemetry
US6961615Feb 7, 2002Nov 1, 2005Pacesetter, Inc.System and method for evaluating risk of mortality due to congestive heart failure using physiologic sensors
US6961617Oct 19, 2001Nov 1, 2005Pacesetter, Inc.Method and apparatus to backup, update and share data among implantable cardiac stimulation device programmers
US6968232Mar 6, 2002Nov 22, 2005Pacesetter, Inc.Method and apparatus for using a rest mode indicator to automatically adjust control parameters of an implantable cardiac stimulation device
US6968233Jun 20, 2002Nov 22, 2005Pacesetter, Inc.Implantable cardiac stimulation device including a system for and method of automatically inducing a tachyarrhythmia
US6970744Aug 13, 2003Nov 29, 2005Pacesetter, Inc.Bioenergy generator
US6973350Mar 31, 2003Dec 6, 2005Pacesetter, Inc.Diagnosis of atrial fusion, atrial pseudofusion and/or native atrial activity
US6975904Nov 8, 2001Dec 13, 2005Pacesetter, Inc.Modification of evoked response detection algorithm based on orientation and activity of patient
US6978175Aug 6, 2002Dec 20, 2005Pacesetter, Inc.System and method for automatically and adaptively segmenting an atrial blanking period
US6988002Nov 25, 2002Jan 17, 2006Cardiac Pacemakers, Inc.Apparatus and method for ventricular rate regularization with biventricular sensing
US6996437Apr 25, 2002Feb 7, 2006Medtronic, Inc.Ventricular safety pacing in biventricular pacing
US7003348Jul 1, 2003Feb 21, 2006Pacesetter, Inc.Monitoring cardiac geometry for diagnostics and therapy
US7006868Mar 6, 2002Feb 28, 2006Pacesetter, Inc.Method and apparatus for using a rest mode indicator to automatically adjust control parameters of an implantable cardiac stimulation device
US7006869Sep 10, 2001Feb 28, 2006Pacesetter, Inc.Method and device for enhanced capture tracking by discrimination of fusion beats
US7024241Dec 5, 2002Apr 4, 2006Pacesetter, Inc.Pacing pulse waveforms that support simultaneous intracardiac signal sensing and analysis
US7031766Apr 20, 2004Apr 18, 2006Pacesetter, Inc.Methods and devices for determining exercise diagnostic parameters
US7039461May 13, 2000May 2, 2006Cardiac Pacemakers, Inc.Cardiac pacing system for prevention of ventricular fibrillation and ventricular tachycardia episode
US7043294Apr 20, 2004May 9, 2006Pacesetter, Inc.Methods and devices for determining heart rate recovery
US7047065Oct 16, 2003May 16, 2006Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US7047066Mar 3, 2004May 16, 2006Cardiac Pacemakers, Inc.Method and system for display of cardiac event intervals in a resynchronization pacemaker
US7062325May 21, 1999Jun 13, 2006Cardiac Pacemakers IncMethod and apparatus for treating irregular ventricular contractions such as during atrial arrhythmia
US7062327May 2, 2002Jun 13, 2006Pacesetter, Inc.Method and apparatus for providing atrial autocapture in a dynamic atrial overdrive pacing system for use in an implantable cardiac stimulation device
US7069077Nov 27, 2002Jun 27, 2006Cardiac Pacemakers, Inc.Rate smoothing control
US7099716 *Jun 3, 2002Aug 29, 2006Pacesetter, Inc.Implantable cardiac stimulation device having autocapture/autothreshold capability
US7117037Jan 27, 2003Oct 3, 2006Cardiac Pacemakers, Inc.Event marker alignment by inclusion of event marker transmission latency in the real-time data stream
US7120490Aug 2, 2002Oct 10, 2006Cardiac Pacemakers, Inc.Cardiac rhythm management system with atrial shock timing optimization
US7120491Mar 12, 2003Oct 10, 2006Pacesetter, Inc.Implantable cardioversion device with a self-adjusting threshold for therapy selection
US7139604Mar 28, 2002Nov 21, 2006Pacesetter, Inc.Cardiac stimulation system and method for discriminating sinus from non-sinus events
US7139607Jun 11, 2003Nov 21, 2006Pacesetter, Inc.Arrhythmia discrimination
US7142915Jun 13, 2003Nov 28, 2006Cardiac Pacemakers, Inc.Apparatus and method for ventricular rate regularization
US7142918Dec 26, 2000Nov 28, 2006Cardiac Pacemakers, Inc.Apparatus and method for pacing mode switching during atrial tachyarrhythmias
US7146213Dec 5, 2003Dec 5, 2006Pacesetter, Inc.Method and apparatus for improving specificity of atrial tachycardia detection techniques in dual-unipolar or dual-bipolar implantable cardiac stimulation systems
US7158829Dec 5, 2003Jan 2, 2007Pacesetter, Inc.Method and apparatus for improving specificity of atrial tachycardia detection techniques in dual-unipolar or dual-bipolar implantable cardiac stimulation systems
US7164944Apr 15, 2003Jan 16, 2007Pacesetter, Inc.Analgesic therapy for ICD patients
US7174210Dec 5, 2003Feb 6, 2007Pacesetter, Inc.Method and apparatus for improving specificity of atrial tachycardia detection techniques in dual-unipolar or dual-bipolar implantable cardiac stimulation systems
US7181276Jul 27, 2004Feb 20, 2007Pacesetter, Inc.Device and method for preventing the acceleration of cardiac arrhythmias
US7181278Mar 20, 2003Feb 20, 2007Cardiac Pacemakers, Inc.Apparatus and method for ventricular rate regularization
US7181280Jan 27, 2004Feb 20, 2007Pacesetter, Inc.System and method of automatically adjusting auto capture safety margin
US7181281Oct 8, 2003Feb 20, 2007Pacesetter, Inc.ICD using MEMS for optimal therapy
US7184834Dec 5, 2003Feb 27, 2007Pacesetter, Inc.Method and apparatus for improving specificity of atrial tachycardia detection techniques in dual-unipolar or dual-bipolar implantable cardiac stimulation systems
US7187972Nov 18, 2004Mar 6, 2007Pacesetter, Inc.Bi-ventricular pacing in the face of rapidly conducting atrial tachyarrhythmia
US7197360Jan 12, 2005Mar 27, 2007Pacesetter, Inc.Methods and systems for using an inductor to increase capacitor reformation efficiency in an implantable cardiac device (ICD)
US7203537Jan 10, 2004Apr 10, 2007Mr3 Medical, LlcSystem and method for breaking reentry circuits by cooling cardiac tissue
US7212859Jul 26, 2002May 1, 2007Pacesetter, Inc.Dual-chamber implantable cardiac stimulation system and device with selectable arrhythmia termination electrode configurations and method
US7212860Nov 13, 2003May 1, 2007Cardiac Pacemakers, Inc.Apparatus and method for pacing mode switching during atrial tachyarrhythmias
US7212863 *Jun 23, 2003May 1, 2007St. Jude Medical AbImplantable medical device operable in a special mode upon activation during a programmed time
US7215999Aug 6, 2003May 8, 2007Pacesetter, Inc.Battery charge indicator for implantable pacemakers and defibrillators
US7223244May 18, 2004May 29, 2007Pacesetter, Inc.System and method for monitoring hypercapnic ventilatory response
US7225017May 28, 2004May 29, 2007Pacesetter, Inc.Parasympathetic nerve stimulation for ICD and/or ATP patients
US7233827Jun 9, 2004Jun 19, 2007Pacesetter, Inc.Implantable cardiac stimulation device with automatic evoked response sensing electrode configuration selection and method
US7239914Dec 12, 2001Jul 3, 2007Cardiac Pacemakers, Inc.Rate smoothing control
US7245965 *Jun 18, 2003Jul 17, 2007Pacesetter, Inc.Implantable cardiac device providing mode switching and automatic atrial sensitivity control and method
US7245967Jun 11, 2003Jul 17, 2007Pacesetter, Inc.Parasympathetic nerve stimulation for termination of supraventricular arrhythmias
US7272438Oct 12, 2004Sep 18, 2007Pacesetter, Inc.Mode switching heart stimulation apparatus and method
US7277761Jun 11, 2003Oct 2, 2007Pacesetter, Inc.Vagal stimulation for improving cardiac function in heart failure or CHF patients
US7283871Apr 7, 2005Oct 16, 2007Pacesetter, Inc.Self adjusting optimal waveforms
US7286872Oct 7, 2003Oct 23, 2007Cardiac Pacemakers, Inc.Method and apparatus for managing data from multiple sensing channels
US7289847Jan 18, 2005Oct 30, 2007Pacesetter, Inc.Implantable cardiac device and method of treating atrial fibrillation
US7295873Jul 15, 2004Nov 13, 2007Pacesetter, Inc.Anti-tachycardia pacing method and apparatus for multi-chamber pacing
US7308305Jul 27, 2004Dec 11, 2007Pacesetter, Inc.Optimally timed early shock defibrillation
US7308308Apr 25, 2005Dec 11, 2007Pacesetter, Inc.Method to monitor progression of atrial fibrillation and to detect its susceptibility for termination
US7308310Jan 26, 2005Dec 11, 2007Pacesetter, Inc.Implantable cardiac stimulation device providing bipolar autocapture and lead impedance assessment and method
US7321792Mar 19, 2003Jan 22, 2008Pacesetter, Inc.Pacing therapy and acupuncture
US7349738Feb 19, 2003Mar 25, 2008Pacesetter, Inc.Detecting atrial evoked response
US7353067Jan 16, 2004Apr 1, 2008Pacesetter, Inc.Implantable leads, electrode portions and methods for securing
US7363077Nov 9, 2004Apr 22, 2008Pacesetters, Inc.Adaptive timing interval control method for treating congestive heart failure
US7363085Jan 26, 2004Apr 22, 2008Pacesetters, Inc.Augmenting hypoventilation
US7363086Mar 21, 2005Apr 22, 2008Pacesetter, Inc.Capture verification in respiratory diaphragm stimulation
US7364550Jun 17, 2004Apr 29, 2008Pacesetter, Inc.Method and device for motion and noise immunity in hemodynamic measurement
US7376461 *Oct 18, 2002May 20, 2008Cardiac Pacemakers, Inc.Dynamic mode switch for early detection of tachyarrhythmia
US7383086Jul 12, 2004Jun 3, 2008Cardiac Pacemakers, Inc.Ventricular conduction delay trending system and method
US7386343Sep 30, 2005Jun 10, 2008Pacesetter, Inc.Spectrum-driven arrhythmia treatment method
US7389140Jun 16, 2004Jun 17, 2008Kroll Mark WAdjustment of stimulation current path
US7398122Apr 7, 2005Jul 8, 2008Pacesetter, Inc.Self adjusting optimal waveforms
US7403813Nov 24, 2004Jul 22, 2008Pacesetter, Inc.Systems and methods for detection of VT and VF from remote sensing electrodes
US7403819Jun 11, 2003Jul 22, 2008Pacesetter, Inc.Parasympathetic nerve stimulation for control of AV conduction
US7421296Jan 26, 2004Sep 2, 2008Pacesetter, Inc.Termination of respiratory oscillations characteristic of Cheyne-Stokes respiration
US7430447Jun 6, 2005Sep 30, 2008Pacesetter, Inc.Evoked response and impedance measures for monitoring heart failure and respiration
US7440800May 31, 2005Oct 21, 2008Mr3 Medical, LlcSystem and method for managing detrimental cardiac remodeling
US7447540Nov 24, 2004Nov 4, 2008Pacesetter, Inc.Systems and methods for detection of VT and VF from remote sensing electrodes
US7460900Sep 14, 2005Dec 2, 2008Pacesetter, Inc.Method and apparatus for detecting ischemia using changes in QRS morphology
US7460908May 24, 2004Dec 2, 2008Cardiac Pacemakers, Inc.System providing ventricular pacing and biventricular coordination
US7471980Dec 22, 2003Dec 30, 2008Cardiac Pacemakers, Inc.Synchronizing continuous signals and discrete events for an implantable medical device
US7515959Mar 31, 2005Apr 7, 2009Medtronic, Inc.Delivery of CRT therapy during AT/AF termination
US7515971Sep 9, 2005Apr 7, 2009Pacesetter, Inc.Left atrial pressure sensor lead
US7519425Oct 18, 2004Apr 14, 2009Pacesetter, Inc.Tiered therapy for respiratory oscillations characteristic of Cheyne-Stokes respiration
US7529588Aug 18, 2005May 5, 2009Pacesetter, Inc.Method and apparatus to backup, update and share data among implantable cardiac stimulation device programmers
US7546159 *Mar 14, 2005Jun 9, 2009Pacesetter, Inc.Subcutaneous cardiac stimulation device, system, and method providing accelerated arrhythmia detection verification and transient rate compensation
US7546161Jan 11, 2006Jun 9, 2009Pacesetter, Inc.Methods for loss of capture and fusion avoidance in biventricular pacing therapy
US7548785Jun 10, 2004Jun 16, 2009Pacesetter, Inc.Collecting and analyzing sensed information as a trend of heart failure progression or regression
US7574259Nov 12, 2004Aug 11, 2009Pacesetter, Inc.Capture threshold and lead condition analysis
US7584005Apr 12, 2006Sep 1, 2009Pacesetter, Inc.Steroid eluting pacing tip electrode
US7587243May 8, 2006Sep 8, 2009Pacesetter, Inc.System and method for verifying capture and/or event sensing during manual threshold evaluations of an implantable cardiac stimulation device
US7590446Nov 10, 2004Sep 15, 2009Pacesetter, Inc.Methods for ventricular pacing
US7613513Jul 1, 2003Nov 3, 2009Pacesetter, Inc.System and method for determining cardiac geometry
US7627366May 6, 2005Dec 1, 2009Pacesetter, Inc.Analysis of polarization information
US7630078Mar 8, 2007Dec 8, 2009Pacesetter, Inc.Calibrating implantable optical sensors
US7636600Oct 21, 2005Dec 22, 2009Pacesetter, Inc.Pressure monitoring for apnea prevention and/or therapy
US7647104Oct 13, 2006Jan 12, 2010Pacesetter, Inc.Ischemia detection using paced depolarization integral and intracardiac electrogram template comparison
US7648464Jul 19, 2006Jan 19, 2010Pacesetter, Inc.Detecting ischemia using an implantable cardiac device based on morphology of cardiac pressure signal
US7650189Jun 2, 2006Jan 19, 2010Pacesetter, Inc.Techniques to maintain or alter upper airway patency
US7660616Sep 20, 2005Feb 9, 2010Pacesetter, Inc.Implantable multi-wavelength oximeter sensor
US7660629Nov 29, 2006Feb 9, 2010Pacesetter, Inc.Device and method for preventing the acceleration of cardiac arrhythmias
US7668590Feb 10, 2006Feb 23, 2010Pacesetter, Inc.Methods and devices for determining exercise diagnostic parameters
US7672729Jan 17, 2007Mar 2, 2010Pacesetter, Inc.Multi-variable feedback control of stimulation for inspiratory facilitation
US7676262Apr 13, 2006Mar 9, 2010Pacesetter, Inc.Methods and devices for determining exercise compliance diagnostics
US7676266Jul 30, 2007Mar 9, 2010Pacesetter, Inc.Monitoring ventricular synchrony
US7680530May 3, 2006Mar 16, 2010Cardiac Pacemakers, Inc.Method and system for display of cardiac event intervals in a resynchronization pacemaker
US7684870Nov 18, 2005Mar 23, 2010Pacesetter, Inc.Direct current fibrillator
US7702390Dec 13, 2006Apr 20, 2010Pacesetter, Inc.Rate adaptive biventricular and cardiac resynchronization therapy
US7738954Apr 22, 2004Jun 15, 2010Pacesetter, Inc.His bundle control
US7742814Apr 25, 2006Jun 22, 2010Cardiac Pacemakers, Inc.Cardiac pacing system for prevention of ventricular fibrillation and ventricular tachycardia episode
US7751892May 6, 2004Jul 6, 2010Cardiac Pacemakers, Inc.Implantable medical device programming apparatus having a graphical user interface
US7756570May 1, 2006Jul 13, 2010Pacesetter, Inc.Methods and arrangements for reducing oversensing and/or providing diagnostic information in implantable medical devices
US7778706Dec 13, 2006Aug 17, 2010Pacesetter, Inc.Rate adaptive biventricular and cardiac resynchronization therapy
US7783355Jan 21, 2004Aug 24, 2010Medtronic, Inc.Dynamic adjustment of capture management “safety margin”
US7785256Jan 11, 2006Aug 31, 2010Pacesetter, Inc.Method and system for displaying patient activity data using Poincaré and intensity plot
US7792572May 16, 2005Sep 7, 2010Pacesetter, Inc.Ischemia detection using intra-cardiac signals
US7805192Oct 13, 2006Sep 28, 2010Cardiac Pacemakers, Inc.Apparatus and method for pacing mode switching during atrial tachyarrhythmias
US7809439Apr 28, 2008Oct 5, 2010Pacesetter, Inc.Spectrum-driven arrhythmia treatment method
US7822472Jul 19, 2006Oct 26, 2010Pacesetter, Inc.Methods and systems for optimizing exercise compliance diagnostic parameters
US7840246Nov 17, 2005Nov 23, 2010Pacesetter, Inc.Implantable self-calibrating optical sensors
US7840264Mar 30, 2007Nov 23, 2010Mr3 Medical, LlcSystem and method for breaking reentry circuits by cooling cardiac tissue
US7844322Apr 24, 2006Nov 30, 2010Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US7844332Feb 19, 2007Nov 30, 2010Cardiac Pacemakers, Inc.Atrioventricular delay adjustment enhancing ventricular tachyarrhythmia detection
US7848793Sep 29, 2006Dec 7, 2010Pacesetter, Inc.Monitoring for mitral valve regurgitation
US7848804Jun 18, 2007Dec 7, 2010Pacesetter, Inc.Apparatus and related methods for capacitor reforming
US7848806Feb 21, 2006Dec 7, 2010Pacesetter, Inc.Virtual electrode polarization for shock therapy
US7850616Jun 15, 2005Dec 14, 2010Pacesetter, Inc.Determination of diastolic heart failure
US7856267Apr 10, 2007Dec 21, 2010Cardiac Pacemakers, Inc.Apparatus and method for pacing mode switching during atrial tachyarrhythmias
US7856271Nov 30, 2007Dec 21, 2010Pacesetter, Inc.Detecting atrial evoked response
US7869875 *May 6, 2005Jan 11, 2011Cardiac Pacemakers, Inc.Cardiac rhythm management system with maximum tracking rate (MTR) hysteresis
US7881786Apr 29, 2005Feb 1, 2011Medtronic, Inc.Suppression of high rate pacing for reducing myocardial ischemic irritability
US7881787Dec 18, 2006Feb 1, 2011Pacesetter, Inc.Capture detection system and method CRT therapy
US7894901Aug 21, 2006Feb 22, 2011Pacesetter, Inc.Apparatus and method for assessing cardiac therapy
US7894915Oct 27, 2006Feb 22, 2011Pacesetter, Inc.Implantable medical device
US7899536May 15, 2007Mar 1, 2011Pacesetter, Inc.Morphology discrimination for capture assessment
US7899537Oct 27, 2006Mar 1, 2011Pacesetter, Inc.Pericardial cardioverter defibrillator
US7908003Jun 15, 2007Mar 15, 2011Mr3 Medical LlcSystem and method for treating ischemia by improving cardiac efficiency
US7908004Aug 30, 2007Mar 15, 2011Pacesetter, Inc.Considering cardiac ischemia in electrode selection
US7912544Apr 20, 2007Mar 22, 2011Pacesetter, Inc.CRT responder model using EGM information
US7917194Nov 15, 2006Mar 29, 2011Pacesetter, Inc.Method and apparatus for detecting pulmonary edema
US7917197Feb 10, 2006Mar 29, 2011Pacesetter, Inc.Methods and devices for determining exercise diagnostic parameters
US7941217Mar 25, 2008May 10, 2011Pacesetter, Inc.Techniques for promoting biventricular synchrony and stimulation device efficiency using intentional fusion
US7953482Feb 20, 2009May 31, 2011Medtronic, Inc.Delivery of CRT therapy during AT/AF termination
US7962203Dec 29, 2003Jun 14, 2011Cardiac Pacemakers, Inc.Arrhythmia display
US7970473Oct 2, 2008Jun 28, 2011Pacesetter, Inc.Systems and methods for detection of VT and VF from remote sensing electrodes
US7972276Apr 26, 2007Jul 5, 2011Pacesetter, Inc.Method for removing posture dependence during evoked response monitoring of HF progression
US7974675Feb 27, 2009Jul 5, 2011Pacesetter, Inc.Method of measuring pressure with a septal lead
US7983765Aug 19, 2005Jul 19, 2011Pacesetter, Inc.Left chamber pressure sensor lead delivery system
US7988634Jan 10, 2007Aug 2, 2011Pacesetter, Inc.Adaptive cancellation of a signal component
US7996086Sep 27, 2010Aug 9, 2011Cardiac Pacemarkers, Inc.Apparatus and method for pacing mode switching during atrial tachyarrhythmias
US8010194Apr 1, 2009Aug 30, 2011David MullerDetermining site-to-site pacing delay for multi-site anti-tachycardia pacing
US8016764Nov 8, 2006Sep 13, 2011Pacesetter, Inc.Systems and methods for evaluating ventricular dyssynchrony using atrial and ventricular pressure measurements obtained by an implantable medical device
US8027719Mar 20, 2008Sep 27, 2011Cardiac Pacemakers, Inc.Method and apparatus for delivering defibrillation shock therapy while reducing electrical dispersion due to ventricular conduction disorder
US8046060Nov 14, 2005Oct 25, 2011Cardiac Pacemakers, Inc.Differentiating arrhythmic events having different origins
US8060200Jun 2, 2008Nov 15, 2011Pacesetter, Inc.Self-adjusting optimal waveforms
US8064997Jun 12, 2006Nov 22, 2011Cardiac Pacemakers, Inc.Method and apparatus for treating irregular ventricular contractions such as during atrial arrhythmia
US8090444Nov 7, 2008Jan 3, 2012Pacesetter, Inc.Optimization of cardiac pacing therapy based on paced propagation delay
US8103334Feb 17, 2010Jan 24, 2012Cardiac Pacemakers, Inc.Method and system for display of cardiac event intervals in a resynchronization pacemaker
US8108053Feb 12, 2009Jan 31, 2012Pacesetter, Inc.Small caliber implantable biometric leads and cables for same
US8126546Jun 30, 2009Feb 28, 2012Pacesetter, Inc.Anodal excitation of tissue
US8126550Jul 22, 2008Feb 28, 2012Pacesetter, Inc.Methods and devices involving automatic atrial blanking
US8126552Oct 21, 2008Feb 28, 2012Pacesetter, Inc.Measurement of cardiac information for CRT optimziation in the presence of conduction dysfunction or atrial arrhythmia
US8131351Nov 8, 2010Mar 6, 2012Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US8135465Dec 1, 2008Mar 13, 2012Cardiac Pacemakers, Inc.System providing ventricular pacing and biventricular coordination
US8150529Apr 16, 2008Apr 3, 2012Pacesetter, Inc.Medical devices and systems having separate power sources for enabling different telemetry systems
US8160700May 16, 2007Apr 17, 2012Pacesetter, Inc.Adaptive single site and multi-site ventricular pacing
US8162842Dec 7, 2009Apr 24, 2012Pacesetter, Inc.Detecting ischemia using an implantable cardiac device based on morphology of cardiac pressure signal
US8165667Sep 16, 2010Apr 24, 2012Pacesetter, Inc.Methods and systems for optimizing exercise compliance diagnostic parameters
US8175707Dec 6, 2007May 8, 2012Pacesetter, Inc.Enhancement of rate responsive IEGM-based AV/PV and VV delay algorithms
US8175723Jul 17, 2009May 8, 2012Pacesetter, Inc.Steroid eluting pacing tip electrode
US8180439Jul 29, 2010May 15, 2012Pacesetter, Inc.Ischemia detection using intra-cardiac signals
US8185200Dec 1, 2008May 22, 2012Cardiac Pacemakers, Inc.Disable for atrioventricular delay adjustment
US8202224Apr 24, 2008Jun 19, 2012Pacesetter, Inc.System and method for calibrating cardiac pressure measurements derived from signals detected by an implantable medical device
US8209005Oct 31, 2006Jun 26, 2012Pacesetter, Inc.System and method for reducing pain in a high-voltage lead impedance check procedure using DC voltage or current in an implantable medical device
US8233978Jul 12, 2004Jul 31, 2012Pacesetter, Inc.Method and device for switching between arrhythmia prevention modes
US8233980May 7, 2008Jul 31, 2012Pacesetter, Inc.System and method for detecting hidden atrial events for use with automatic mode switching within an implantable medical device
US8239021Jun 15, 2010Aug 7, 2012Cardiac Pacemakers, Inc.Cardiac pacing system for prevention of ventricular fibrillation and ventricular tachycardia episode
US8249703Feb 9, 2007Aug 21, 2012Cardiac Pacemakers, Inc.Apparatus and method for ventricular rate regularization
US8255051May 19, 2010Aug 28, 2012Pacesetter, Inc.Skin response monitoring for neural and cardiac therapies
US8255062Jun 9, 2011Aug 28, 2012Pacesetter, Inc.Left chamber pressure sensor lead delivery system
US8260407Aug 28, 2006Sep 4, 2012Pacesetter, Inc.Intracardiac device and method for storing cardiac test results and associated EGM data
US8265738Feb 3, 2011Sep 11, 2012Pacesetter, Inc.CRT responder model using EGM information
US8265739Jan 17, 2008Sep 11, 2012Pacesetter, Inc.Systems and methods for distinguishing cardiac ischemia from systemic influences on IEGM morphology using an implantable medical device
US8290585Jan 21, 2002Oct 16, 2012Mr3 Medical, LlcAugmentation of electrical conduction and contractility by biphasic cardiac pacing administered via the cardiac blood pool
US8301246Jun 7, 2007Oct 30, 2012Pacesetter, Inc.System and method for improving CRT response and identifying potential non-responders to CRT therapy
US8328728Aug 22, 2008Dec 11, 2012Pacesetter, Inc.Implantable hemodynamic monitor and methods for use therewith
US8343059Feb 23, 2007Jan 1, 2013Pacesetter, Inc.Identifying left atrial pressure elevation by means of a respiratory component
US8374691Jan 10, 2011Feb 12, 2013Pacesetter, Inc.Methods and systems for determining if an arrhythmia initiated in an atrium or a ventricle
US8388670Jan 16, 2007Mar 5, 2013Pacesetter, Inc.Sensor/lead systems for use with implantable medical devices
US8391974Dec 20, 2010Mar 5, 2013Cardiac Pacemakers, Inc.Apparatus and method for pacing mode switching during atrial tachyarrhythmias
US8391977Jan 17, 2012Mar 5, 2013Pacesetter, Inc.Measurement of cardiac information for CRT optimziation in the presence of conduction dysfunction or atrial arrhythmia
US8442634Dec 4, 2008May 14, 2013Pacesetter, Inc.Systems and methods for controlling ventricular pacing in patients with long inter-atrial conduction delays
US8447399Apr 1, 2008May 21, 2013Mr3 Medical, LlcSystem and method for managing detrimental cardiac remodeling
US8452389Jul 7, 2009May 28, 2013Pacesetter, Inc.Criteria for monitoring intrathoracic impedance
US8463369Jun 13, 2011Jun 11, 2013Cardiac Pacemakers, Inc.Arrhythmia display
US8478403Feb 23, 2011Jul 2, 2013Pacesetter, Inc.Implantable systems and methods for use therewith for monitoring and modifying arterial blood pressure without requiring an intravascular pressure transducer
US8498706Jul 1, 2009Jul 30, 2013Pacesetter, Inc.Capture threshold and lead condition analysis
US8512220Jun 7, 2007Aug 20, 2013Cardiac Pacemakers, Inc.Rate smoothing control
US8540643Feb 29, 2008Sep 24, 2013Pacesetter, Inc.Method and device for motion and noise immunity in hemodynamic measurement
US8548576Mar 2, 2012Oct 1, 2013Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US8560056Aug 1, 2012Oct 15, 2013Pacesetter, Inc.Intracardiac device and method for storing cardiac test results and associated EGM data
US8565875Dec 13, 2010Oct 22, 2013Cardiac Pacemakers, Inc.Cardiac rhythm management system with maximum tracking rate (MTR) hysteresis
US8583219Aug 1, 2012Nov 12, 2013Pacesetter, Inc.Intracardiac device and method for storing cardiac test results and associated EGM data
US8600490Nov 21, 2007Dec 3, 2013Pacesetter, Inc.Two-dimensional refractory period
US8620424Apr 30, 2007Dec 31, 2013Medtronic, Inc.Method and apparatus for providing extra systolic stimulation
US8694094May 16, 2007Apr 8, 2014Pacesetter, Inc.Adaptive single site and multi-site ventricular pacing
US8702616Nov 10, 2010Apr 22, 2014Pacesetter, Inc.Determination of diastolic heart failure
US8709631Apr 19, 2007Apr 29, 2014Pacesetter, Inc.Bioelectric battery for implantable device applications
US20100298901 *Apr 30, 2010Nov 25, 2010Medtronic, Inc.Implantable medical device for cardiac electrical stimulation
US20110202103 *Feb 18, 2011Aug 18, 2011Birgitte WikmanWakeup of implantable communication circuitry
US20110213260 *Feb 26, 2010Sep 1, 2011Pacesetter, Inc.Crt lead placement based on optimal branch selection and optimal site selection
EP0360668A2 *Sep 14, 1989Mar 28, 1990Medtronic, Inc.Dual chamber rate responsive pacemaker
EP0488904A1 *Nov 29, 1991Jun 3, 1992ELA-MEDICAL (Société Anonyme)Method for controlling a pacemaker of type DDD with automatic switching of the operation mode
EP0526798A1 *Jul 21, 1992Feb 10, 1993Pacesetter, Inc.Rate-responsive dual-chamber pacemaker
EP0559193A2 *Mar 4, 1993Sep 8, 1993Pacesetter, Inc.Implantable pacemaker providing hysteresis in dual-chamber modes
EP0726082A2Feb 7, 1996Aug 14, 1996Pacesetter Inc.Rate responsive cardiac pacemaker
EP0836866A2 *Sep 17, 1997Apr 22, 1998Pacesetter, Inc.Pacemaker with improved detection of atrial fibrillation
EP0872260A2Apr 14, 1998Oct 21, 1998Pacesetter Inc.Implantable pacemaker
EP1038548A2Mar 22, 2000Sep 27, 2000Pacesetter, Inc.Pacemaker
EP1078651A2Aug 25, 2000Feb 28, 2001Pacesetter, Inc.Implantable pacemaker and method of detecting a pacemaker mediated tachycardia
EP1109593A1 *Sep 2, 1999Jun 27, 2001Cardiac Pacemakers, Inc.Cardioverter and method for cardioverting an atrial tachyarrhythmia while maintaining atrial pacing
EP1118307A1Jan 18, 2001Jul 25, 2001Pacesetter, Inc.An implantable cardiac device for and method of monitoring progression or regression of heart disease
EP1118351A2Jan 17, 2001Jul 25, 2001Pacesetter, Inc.Implantable cardiac stimulation device having autocapture/autothreshold capability
EP1127587A2Jan 24, 2001Aug 29, 2001Pacesetter, Inc.Dual-chamber implantable cardiac stimulation system and device with selectable arrhythmia termination electrode configurations and method
EP1155711A2May 15, 2001Nov 21, 2001Pacesetter, Inc.Method and apparatus for biventricular stimulation and capture monitoring
EP1155712A2May 15, 2001Nov 21, 2001Pacesetter, Inc.Implantable dual site cardiac stimulation device having independent automatic capture capability
EP1184050A2Sep 4, 2001Mar 6, 2002Pacesetter, Inc.Implantable cardiac stimulation device with automatic evoked response sensing electrode configuration selection and method
EP1291038A2Sep 10, 2002Mar 12, 2003Pacesetter, Inc.Pacemaker with enhanced capture tracking
EP1327461A1Jan 8, 2003Jul 16, 2003Pacesetter, Inc.Method and apparatus for dynamically adjusting a non-linear overdrive pacing response function
EP1327462A1Jan 8, 2003Jul 16, 2003Pacesetter, Inc.Method and apparatus for dynamically adjusting overdrive pacing parameters
EP1486232A2Jun 10, 2004Dec 15, 2004Pacesetter, Inc.Device for improving cardiac funtion in heart failure or CHF patients
EP1529551A1Nov 5, 2004May 11, 2005Pacesetter, Inc.Systems for ventricular pacing
EP1557195A1Jan 26, 2005Jul 27, 2005Pacesetter, Inc.Tiered therapy for respiratory oscillations characteristic of cheyne-stokes respiration
EP1598093A2May 19, 2005Nov 23, 2005Pacesetter, Inc.System for automated fluid monitoring
EP1604705A1Jun 9, 2005Dec 14, 2005Pacesetter, Inc.Collection and analysis of information concerning heart failure
EP1634617A1Sep 9, 2005Mar 15, 2006Pacesetter, Inc.Multi-variable feedback control of stimulation inspiratory facilitation
EP1698276A1Mar 3, 2006Sep 6, 2006Pacesetter, Inc.Endocardial pressure differential sensing systems
EP1764034A2Sep 20, 2006Mar 21, 2007Pacesetter, Inc.Implantable self-calibrating optical sensors
EP1982647A2Apr 21, 2008Oct 22, 2008Pacesetter, Inc.Pressure measurement-based ischemia detection
EP2030564A2Jul 25, 2008Mar 4, 2009Pacesetter, Inc.Implantable systemic blood pressure measurement systems and methods
EP2322242A1Nov 12, 2010May 18, 2011Pacesetter, Inc.Mri signal filtering for implantable medical device
EP2636426A1Mar 6, 2013Sep 11, 2013Pacesetter, Inc.RF-powered communication for implantable device
WO1992016258A1 *Feb 4, 1992Oct 1, 1992Medtronic IncDual chamber rate responsive pacemaker with automatic mode switching
WO1994011061A1 *Nov 12, 1993May 26, 1994Siemens PacesetterAdaptative av interval pacemaker
WO1998026839A1Dec 16, 1997Jun 25, 1998Medtronic IncMethod and apparatus for diagnosis and treatment of arrhythmias
WO2000013742A1Sep 2, 1999Mar 16, 2000Cardiac Pacemakers IncCardioverter and method for cardioverting an atrial tachyarrhythmia while maintaining atrial pacing
WO2000038782A1Dec 22, 1999Jul 6, 2000Medtronic IncRegularization of ventricular rate during atrial tachyarrhythmia
WO2006118846A2 *Apr 24, 2006Nov 9, 2006Medtronic IncSuppression of high rate pacing for reducing myocardial ischemic irritability
WO2012115976A1Feb 21, 2012Aug 30, 2012Advanced Neuromodulation System, Inc.Method for fabricating an implantable lead for applying electrical pulses to tissue of a patient and system for fabrication thereof
Classifications
U.S. Classification607/14, 607/30
International ClassificationA61N1/365, A61N1/362
Cooperative ClassificationA61N1/3622
European ClassificationA61N1/362A2
Legal Events
DateCodeEventDescription
Apr 22, 2008B1Reexamination certificate first reexamination
Free format text: CLAIMS 1-9, 11, 12 AND 14-18 ARE CANCELLED. CLAIMS 10, 13, 19 AND 20 ARE DETERMINED TO BE PATENTABLE AS AMENDED. NEW CLAIMS 21, 22, 23, 24 AND 25 ARE ADDED AND DETERMINED TO BE PATENTABLE.
Jun 24, 2003RRRequest for reexamination filed
Effective date: 20030519
Feb 20, 2002REMIMaintenance fee reminder mailed
Jan 30, 2002FPAYFee payment
Year of fee payment: 12
Jan 20, 1998FPAYFee payment
Year of fee payment: 8
Mar 23, 1995ASAssignment
Owner name: PACESETTER, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SIEMENS PACESETTER, INC.;REEL/FRAME:007388/0042
Effective date: 19940930
Dec 20, 1993FPAYFee payment
Year of fee payment: 4
May 23, 1989ASAssignment
Owner name: SIEMENS-PACESETTER, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SHOLDER, JASON A.;REEL/FRAME:005079/0346
Effective date: 19890523